By the time he _____ back last night, we had got 200 pictures of the Chang'e-3 lunar probe.
Not only I but also Jane and Mary _______ tired of doing the same thing all the time.
Getting _______ in the forest is very dangerous. A. losing B to lose C. lost D. being lost
When traveling abroad, we should ______ learn more about local customs so as to avoid unnecessary misunderstanding during communication.
-- Not knowing what style of iPad to choose, _______.
It seems that living green is ______ easy and cheap. A small step can be rewarded with long-term benefits.