① He half-closed his eyes as though (he were) trying to recall something.
② She leaned there rigid, as if (she were) pinned to the tiles.
③ She ran forward as if (she were) to take the baby in her arms.
④ She shuddered as if (she were) in a terrible thunderstorm.
⑤ Though (he was) worn with fatigue, excitement would not allow him to sleep.
⑥ This is a good if not perfect answer.
=This is a good, if (it is) not perfect (answer), answer.
⑦ It was now nearly if not altogether daylight.
⑧ It is said that the lobster when washed ashore makes no effort to get back into the water, but waits for the sea to come to him. If it does, well and good; if it does not, he simply dies.
=It is said that the lobster when (he is) washed ashore makes no effort to get back into the water, but waits for the sea to come to him. If (it=the sea) (does=comes to him), (he is) well and good; if it does not (come to him), he simply dies.
⑨ You can use this typewriter, whenever (it is) necessary.
⑩ There are strong grounds for teaching foreign languages, if (they teach foreign languages) at all, at an early age.
⑪ Correct errors, if any.
= Correct errors, if (there are) any (errors).
⑫ The talkie was able to do with ease what the silent film had frequently done, if (it had done it) at all, only with the greatest difficulty.
⑬ If it clears up, we will start; if not, not.
⑭ If there are daggers, the likelihood is that sooner or later there will be stabbing; if armaments wars.
⑮ The university must fit its students for society, says Newman. But what (shall I do / will happen) if there is no society for which they can be made fit?
⑯ What (does it matter) if I fall ill? The doctor lives nearby.