She studies very hard, because she doesn't want to ______ her parents ______.[ ]

A. let; up

B. let; down

C. make; up

D. stay; up

在背书转让汇票时未记载日期的，视为在( )背书。

A．出票日

B．汇票到期日前

C．汇票提示承兑日之前

D．汇票提示付款日之前