It is necessary that the students ____ more excercises to do.
A、haveA
【句意】學生們有必要做更多的練習。
【難點】虛擬語氣可以用于主語從句中，常用的句型為：It+is(was)+形容詞that…，主語從句中的謂語用(should)+v.的表達形式。
Mr.Greenisusedto_________twoapplesafterluncheveryday.
Oneoftherequirementsforafireisthatthematerial____toitsburningtemperature.
Itisnecessarythatthestudents____moreexcercisestodo.
Thepresentsituationforcedusto____thispolicy.
Iam____gratefulforthemanykindnessesyouhaveshownmyson.
