— Mum, would you please buy me an MP5 player?
— If you can help do some housework the whole vacation，you have one as a reward.
A. must
B. need
C. would
D. shall
网友回答
A. must
B. need
C. would
(答案→)D. shall
解析：考查情态动词用法。Must一定，必须；B需要；C会；shall用语二，三人称表示命令，警告，强制，允诺，（法律规定中要做的事情）；结合句意可知D正确，表示妈妈的允诺。句意：—妈妈，你能给我买一个MP5吗？—如果在假期里你能帮我做家务，你就会得到一个MP5.