When _______ at the door, she was given a warm welcome.

When _______ at the door, she was given a warm welcome.
A、 appears
B、 appearing
C、 to appear
D、 appeared
【正确答案】：B

上一篇： He was warned _______ he should make the same mistake again.

下一篇： Look at the terrible situation I am in! If only I _________ you