问题

Bad habits, _______ formed, are difficult, and sometimes impossible to shake off

A:before
B:adonce
C:until
D:unless

正确答案是：

同类题型

________________ —-He’s very fine. Thank you.

My grandmother always treats others with _______.

What can I do for you– I’d like to buy a present for my son, _______ at aproper price but of great use.

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