注销税务登记，各涉税事项办结后（）工作日内办结。
A、2个
B、3个
C、5个
D、7个
参考答案：A
—Tom graduated from college at a very young age.
—Oh, he ______ have been a very smart boy then.[ ]
A. should
B. can
C. must
D. will
ETF份额的申购和赎回可以采用组合证券和资金相结合的方式进行。 ( )
