20.　 She d ________ a talk on philosophy during her visit to her mother school.

19.　 A number of parents have v _______ concern about their children’s safety.

18.　 Matter has three states . For example, water is ___________(液体).

17.　 I think that we have many o __________ of meeting interesting people on the train when traveling.

16.　 He has an e __________ talent for music.

15.　 He seems to be honest and trusted, but in r ________ he often tells lies.

14.　 The decision was c ________ by all the members.

13.　 This machine is used to ___________ (监测) a patient’s pulse.

12.　 The child was t __________ at the piano his parents sent to him on his birthday.

11.　 My computer c ________ suddenly last night and all of my documents I was working on got lost.