The bank closes at 3:00 p.m. 银行在3点关门。

(1) 改成以“什么时候” When 开头的疑问句
—> When does the bank close? 银行什么时候关门？

(2) 改成附加疑问句
—> The bank closes at 3:00 p.m., doesn't it? 银行在3点关门是吗？ 

(3) 改为用 cannot “不可能……”和 2:00 p.m.“2点钟”表示“银行不可能在2点关门。”
—> The bank cannot close at 2:00 p.m.

I stand in line at the cash register. 我在收银台排队。

(1) 改为过去时

—> I stood in line at the cash register. 我在收银台排队了。（stand“站”的过去时是 stood）

(2) 改为以 she 为主语的过去时疑问句

—> Did she stand in line at the cash register? 她在收银台排队了吗？

(3) 改为现在完成进行时 have been doing，并加上 for twenty minutes 表示“我在收银台前排了20分钟队。”

—> I have been standing in line at the cash register for twenty minutes.