单项选择题
A.caused B.because C.due D.because of
The mistake was（）by carelessness of the assistant.A.due...
单项选择题The mistake was（）by carelessness of the assistant.
A.due B.caused C.because D.owe
The volunteers started looking after other children（）pa...
单项选择题The volunteers started looking after other children（）parents died of AIDS last year
A.whose B.that C.which D.who
I started looking after other children（）parents went ou...
单项选择题I started looking after other children（）parents went out to work.
A.who B.which C.whose D.that
