529.Peter,where did you guys go for the summer vacation?
We ______ busy with our work for months,so we went to the beach to relax ourselves.
A.were
B.have been
C.had been
D.will be
530.When you are home,give a call to let me know ____ safely.
A.are arriving
B.have arrived
C.had arrived
D.will arrive
529.答案是C;该动作在went for the summer vacation之前，为过去的过去，应用过去完成时。
530.答案是B;根据句意此处只能用现在完成时。
