The conditional clause is often called the protasis, and the conclusion is often called the apodosis.
The conclusion of a conditional sentence may be declarative, interrogative, imperative, or exclamatory.
- If you go to Philadelphia, where shall you stay? [Interrogative.]
- Sit here, if you wish. [Imperative.]
- If you win the prize, how glad I shall be! [Exclamatory.]
413. A conditional clause may be introduced by provided (or provided that), granted that, supposing (or suppose), on condition that.
- I will permit you to go, on condition that you come home early.
- You may have the money, provided you will put it in the bank.
- Supposing (or suppose) it rains, what shall we do?
Suppose is really an imperative and supposing a participle, the clause being the object.
414. A negative condition is commonly introduced by if ... not or unless.
- I will wait for him, if you do not object.
- Unless you overcome that habit, you will be ruined.
415. Double (or alternative) conditions may be introduced by whether ... or.
- Whether he goes or stays, he must pay a week’s board. [Compare: If he goes or if he stays, etc.]
- He is determined to buy that car, whether you approve or not. [That is: if you approve or if you do not approve.]