When we talk about emotions expressed by the body, we naturally think of a lot of meanings of the action. For example, applauding means _____.

He has come across in his research a tricky question, which left him __________ an answer in the darkness. A: applauding for B: striving for C: standing for D: groping for

Which of the following statements about communication by hearing is true（） A: Communication by hearing is more important than communication by sight. B: Whistling and applauding are the only two forms of communication by hearing. C: Handshaking, as well as hand-stroking, has enabled the blind to communicate by hearing. D: It is possible to communicate intelligently by hearing.