问题
选择题
Mary clapped her hand over her mouth _______ she realized what she had said.
A．while
B．as soon as
C．suddenly
D．then
答案
B。
根据语境可推知。如下面一题也选as soon as：
_______ he became rich he cast aside all his old friends who gave him some help.
A. While B. As soon as
C. Suddenly D. Then