Key
1. 胆小的                 （and表示反义词关系） 2. 犹豫不决的             （that is表示解释说明） 3. 退出                   （or表示同义词关系） 4. 谬论                   （who引导的定语从句表示下定义） 5. 座谈小组               （破折号表示解释说明） 6. 固执的，倔强的         （第二句复述前面的内容）

1. Tom and his twin brother differ in their character. Tom is brave while Jim is timid.

2. He is hesitant, that is, he tends to hesitate when it comes to a decision.

3. Many people wanted to secede or withdrew from this union. 

4. Some people have fallacy in terms of racial problem, who hold mistaken attitudes
　 towards it. 

5. This television program will invite a special panel ─ a group of speakers to answer the
　 audience’s questions.    

6. She is rather stubborn. Once she is determined to do a thing, it is difficult to persuade
　her to give up her idea.