1 . All of us find ____________ meaningful to be volunteers. (用适当的词填空)

2 . I find ________difficult to communicate with strangers. (用适当的词填空)

3 . Believe ___ or not, all such possibilities should be considered while you are dealing with this problem.

4 . As you know, _______ is a fact that English is being accepted as an international language. （用适当的词填空）