1 . The research reveals that teenagers find ________ difficult to concentrate on their study after playing mobile games continuously for an hour. (用适当的词填空)

3 . ________ shocked us that as many as 100 species of fish, some unique to these waters, may have been affected by the pollution. (用适当的词填空)

4 . __________is not unusual to see American university students drive to school every day. (用适当的词填空)

5 . When we miss a night’s sleep, we find ________harder the next day to concentrate on learning new information. (用适当的词填空)

6 . They should make ________ clear for us to know how to operate the machine.(用适当的词填空)

7 . When in college, I found ______ difficult to get along with my roommates. (用适当的词填空)

8 . I feel ________ our responsibility to protect and pass on our outstanding traditional culture. (用适当的词填空)

9 . __________ is not uncommon for teenagers to be lost in computer games. (用适当的词填空)

10 . I would appreciate ________ if you could let me know in advance whether you will come or not. (用适当的词填空)