求英語(yǔ)高手識(shí)別一下這三道題共同屬于哪一類語(yǔ)法點(diǎn)(語(yǔ)法知識(shí))?
19.Read it aloud so that I ____ you clearly.
A.may hear B.will hear C.hear D.have heard
20.They got up early in order that they ____ they first train.
A.caught B.will catch C.might catch D.shall catch
21.I am sorry that he ____ in such poor health.
A.are B.shall be C.were D.should be