1.it was his doctor who advised that he have a holiday away from the city.
因為這是he should have ...的簡稱,這里省略should了.這是很典型的英語句型.
2 it is essential that all these figures_twice.
這里不能選A,而應(yīng)選B：be checked,即all these figures (should) be checked twice.同理.
3.這取決與前面有否已有動詞.如 He was killed.
He got killed.
相信幫您解決了難題.不明白的再問喲,請及時采納.那像第一題，主語是he，have在一般句式里應(yīng)該用has，但在虛擬語氣里用should+動原是不是也要把has變成have太對了！看來你掌握了訣竅。1的選項是A. have。 老實(shí)說，有些老師都不懂這個句型呢！