They stopped talking about the _(pleasant) topic at once,because it made them feel uncomfortable.

They stopped talking about the _(pleasant) topic at once,because it made them feel uncomfortable.
(2)The number of the group members __ __ __ more than 200 since then.自那时以来,这个小组的成员数已经增加了200多.
（3）With the help of her Chinese teacher,she __ __ __ the report.在她的语文老师的帮助下,她成功地完成了那个报告.