Pleasewriteareport_______theabovesubjectsaretobecovered.
B
in which the above subjects are to be covered 是 report 的定语从句。 which 指代先行词report，in 用于与 report 搭配。
Neverbefore_______sorapidlydevelopingasitistoday．
Thefarmingmethodshavebeen________improvedwiththeinventionofthenewmachine.
Theyshouldtryto________theirusualinhibitionsandjoininthefun.