Modern forms of transportation and communication have done much to ______ the isolation(隔离)of life in Alaska.
When you learn a foreign language, ________you must forget your own one.
Mark ______ a basketball game in the stadium that _______ 5000 people.
The conference has been held to discuss the effects of tourism ______ the wildlife in the area.
Our son doesn’t know what to _____ at the university; he can’t make up his mind about his future.
We won’t give up _____ we should fail ten times.