问题
选择题
______the doors were closed and that all the lights were off, the boy left the classroom.
A．Check
B．To check
C．Checked
D．Having checked
答案
答案：D
考查非谓语动词。the boy和check是主谓关系，故用主动；check和leave有先后关系，应该用完成时。故选D。