573.Though he is in his late sixties,the well-known biologist begins each day _________ a sense of adventure and a sense of curiosity.
A.in
B.with
C.of
D.at
574.It was clear that the small grocery was _________ people he owed money to.
A.at the expense of
B.at the risk of
C.in the way of
D.at the mercy of
573.答案是B;begin with 以…开始。
574.答案是D;at the expense of 以…为代价；at the risk of 冒着…的危险；at the mercy of 任凭…的摆布，听任。
