THE   CONDITIONAL   SENTENCE                     131

from what I have seen, I shall be compelled to dismiss you.
II. If you have weapons enough, send me a few. 12. If you do
not at once seize the top of the mountain, you will be compelled
to retire. 13. If your line shall extend to the river bank, the
river itself will defend you on that wing. 14. If you finish the
work of the fortifications before the enemy makes an attack
upon you, you can hold out a long time, for you have enough
provisions for the army. 15. I shall not join battle with the
enemy unless the commander arrives to-morrow. 16. If you
will not retreat, fight; for if you fight with me, I can whip you.

I. The sentences involving negative conditions in this exercise
may well be omitted with second-year students. 2. ' not be able.^
3. Abl, 34,/.    4. de.

LESSON   XXX

THE CONDITIONAL SENTENCE (Continued)

161.   Mixed conditions.

The protasis and the apodosis may lie in different times of
the same class, or even in different classes; but each clause
conforms strictly to the laws of its own time and class. The
condition is then called a mixed condition.

// our commander had lived, we should now be free, si imperator
noster superfuisset, liberi nunc essemus; if I am ngt mistaken, he
will make a night attack on you, nisi fallor, vos noctu aggredietur.

162.   Conditional clauses of comparison, or clauses of im¬
aginative comparison.

Clauses akin to conditions are those introduced by as if, just
as if, and called conditional clauses of comparison. They are
introduced in Latin by velut si, ac si, quam si, and have the
verb in the subjunctive, its tense being determined by the law
of sequence of tenses and not by the apparent class of the
condition.