Before going to bed, she _______ that the door was locked.

Before going to bed, she _______ that the door was locked.
A、insured herself
B、assured
C、assured herself
D、insured
【正确答案】：C
【题目解析】：insure确保，保证；assure使确信，弄清楚  assure that+从句，意为“确信......"。
句意：睡觉前，她确信门已经锁上了。