13.The old lady,_____ had been killed in the war,was given help by the local government.

13.The old lady,_____ had been killed in the war,was given help by the local government.
A.all her children B.all of her children
C.all of whose children D.whose all children
16.---What new subject are you going to have in _____ second grade?
---I’m going to learn _____ second foreign language.
A.at,the B.the,a C.the,/ D./,a
18.Why is ___ you are so late for the class?
A.it that B.that it C.it D.that
20._____ we are doing has never been done before.
A.That B.What C.Which D.Whether