It is necessary that the students ____ more excercises to do.
A
【句意】学生们有必要做更多的练习。
【难点】虚拟语气可以用于主语从句中，常用的句型为：It+is(was)+形容词that…，主语从句中的谓语用(should)+v.的表达形式。
—Haveyoufinishedthework?
—Notyet,butnomatterhowharditis,we'llkeep___untilwemakeit.
Ihopeyouwillspendasmuchtimeasyoucan________yourEnglish.
Oneoftherequirementsforafireisthatthematerial____toitsburningtemperature.
____whatmay,we’renotgoingtomakeanyconcessionstohisunreasonabledemands.
It’snecessary_________usallto________