multi: nominative masculine plural; this adjective modifies cives.
cives: nominative plual masculine of the 3rd declension noun civis, civis. This noun could be masculine or feminine, but here it has to be masculine since the adjective modifying it is masculine. Remember also, this is one of the third declension "I-stem" nouns.
aut: this conjunction means "or"; often, we see aut…aut. When this happens, and id does here, we translate the words as "either…or…".
ea: accusative neuter plural of the demonstrative is, ea, id. Since (in its first appearance in this sentence) it modifies pericula (it "demonstrates" which dangers in particular), it agrees with it in number, case and gender. Pericula is the direct object of vident.
pericula: accusative plural neuter of the 2nd declension noun periculum, periculi (n.). It is accusative because it is the direct object of vident.
quae: accusative plural neuter of the relative pronoun qui, quae, quod. It refers back to pericula; so it takes its number and gender from that. It gets its case from its own clause: it is the direct object of the relative clause, si it's in the accusative.
imminent: 3rd person plural present active indicative of the 2nd conjugation verb immineo, imminere. This verb is within a relative clause, introduced by quae.
vident: 3rd person plural present active indicative of the 2nd conjugation verb video, videre, vidi, visum. This first occurence of this verb is also the first of two main verbs (the other one is neglegunt).
ea: this second occurence of ea is as a demonstrative pronoun (in other words it stands in for pericula rather than standing next to it). It is neuter and plural because it replaces pericula; and it is accusative because it is the direct object of neglegunt.
quae: accusative plural neuter of the relative pronoun qui, quae, quod. It refers back to pericula; so it takes its number and gender from that. It gets its case from its own clause: it is the direct object of the relative clause, si it's in the accusative.
vident: 3rd person plural present active indicative of the 2nd conjugation verb video, videre, vidi, visum. This second occurence of the verb in this sentence is within a relative clause, introduced by quae.
neglegunt: 3rd person plural present active indicative of the 3rd conjugation verb neglego, neglegere, neeglexi, neglectum. This is the 2nd main verb in the sentence (the first is the first appearance of vident).
Many citizens either don't see those dangers which are threatening, or they ignore those which they see.
- Turbam vita. Cum his vive qui te meliorem facere possunt; illos admitte quos tu potes facere meliores.
turbam: accusative feminine singular of the 1st declension noun turba, turbae (f.). It is accusative because it is the direct object of the imperative vita.
vita: 2nd person singular present active imperative of the verb vito, vitare, vitavi, vitatum (to avoid, shun).
cum: here, cum is a preposition; as such it takes the ablative case (his).
his: ablative plural masculine of the demonstrative hic, haec, hoc. It is ablative after the preposition cum. This is an example of the "ablative of accompaniment".
vive: 2nd person singular present active Imperative, from the 3rd conjugation verb vivo, vivere, vixi, victum.
qui: nominative masculine plural of the relative pronoun qui, quae, quod. It refers to his (these men) so it takes its number and gender from that. But it is the subject in its own clause, so it has to be in the nominative case.
te: accusative singular of the 2nd person singular personal pronoun. It is the direct object of facere.
meliorem: accusative singular masculine/feminine (depending on what gender "you" is) of the comparative adjective melior, melius. This is the irregular comparative of the positive adjective bonus, bona, bonum.
facere: present active infinitive of the 3rd "io" verb facio, facere, feci, factum. It is a complementary infinitive after possunt.
possunt: 3rd person plural present indicative active of possum, posse, potui.
illos: accusative plural masculine of the demonstrative ille, illa, illud. It is accusative because it is the direct object of admitte.
admitte: 2nd person singular present active Imperative of the 3rd conjugation verb admitto, admittere, admisi, admissum.
quos: accusative masculine plural of the relative pronoun qui, quae, quod. It refers to illos (those men) so it takes its number and gender from that. Since it is the direct object of its own clause, it is accusative.
tu: nominative singular of the 2nd person singular personal pronoun. It is used here for emphasis.
potes: 2nd person singular present active indicative of the irregular verb possum, posse, potui.
meliores: accusative plural masculine of the comparative adjective melior, melius. This is the irregular comparative form from the positive adjective bonus, bona, bonum. It modifies illos…quos.
Avoid confusion. Live with these (men) who can make you better; let in those (men) whom you can make better.