Don"t put off till tomorrow ______ you can do today.
【正确答案】 B
【答案解析】解析:引导宾语从句及其他名词性从句时,that和whether在从句中不充当成分,而 what和when要充当成分,what常在从句中充当主语或宾语。该句中what在从句中作宾语。