Question 20 is based on the passage you have just heard.

    At school and at work, I have noticed that people have different kinds of work habits. Some people are collaborators, who like to work in groups. They find that doing a project with someone else makes the job more pleasant and the load lighter. (20) Collaborators never work alone unless they are forced to. A second category I had noticed is the advice-seeker. An advice-seeker does the bulk of her work alone, but frequently looks to others for advice. When this worker has raised a crucial point in her project, she may show it to a classmate or a co-worker just to get another opinion. (21) Getting the advice of others makes this worker feel secure about her project as it takes shape. Another type of worker I have noticed is the slacker. (22) A slacker tries to avoid work whenever possible. If he seems to be busy at the computer, he is probably playing a game online. And if he is writing busily, he’s probably making his grocery list. Slackers will do anything except the work they are paid to do. The final type of worker is the loner. This type of worker prefers working alone. (21) This type of worker has confidence in his ability, and is likely to feel that collaboration is a waste of time. (20) Loners work with others only when they are forced to. Collaborators, advice-seekers, slackers and loners have different work styles, but each knows the work habits that help him or her to get the job done.

20. What do collaborators and loners have in common?

正确答案：D

解析：短文开头提到，合作者从来不单独工作，除非被逼无奈。结尾处提到，孤独者只有在被逼无奈时才会与他人共事。由此可知，二者的共同之处在于除非被逼无奈，否则他们不会主动改变工作习惯。