Peter was so excited ______he received an invitation from his friend to visit Shanghai. 

_______we admit that there are still some problems about NMET,we don’t mean that it is of no use.

—Will you come?—________you promise not to invite Mary.

______ is often the case is that Tom doesn’t study hard and fails in passing an exam.

Mountain climbing ________ be very tiring, and many people feel sick ________ the atmosphere gets thinner.