My son goes to cram school every evening. 我儿子每天晚上都去上补习班。

(1) 主语改为复数
—> My sons go to cram school every evening. 我的儿子们每天晚上都去上补习班。

(2) 改为 You 为主语的附加疑问句
—> You go to cram school every evening, don't you? 你是每天晚上去补习班吗？/ 你每天晚上去补习班，是吗？ 

(3) 主语改为 you 并改为表示“一星期多少次……”为开头的疑问句 （问“多少次”的疑问句可以 How often...? How many times...? 的句型）
—> How often do you go to cram school a week? 
      How many times do you go to cram school a week? 你一个星期去多少次补习班？

The children are playing cards in the living room. 孩子们在客厅玩扑克牌。

(1) 改为过去时的疑问句
—> Were the children playing cards in the living room? （过去的某个时间段）孩子们在客厅玩扑克牌吗？

(2) 句子开头加 I think “我想……，我认为……”
—> I think the children are playing cards in the living room. 我想孩子们正在客厅玩扑克牌。

(3) 改为用 may 表示的“也许……，可能……”的句子
—> The children may be playing cards in the living room. 孩子们也许正在客厅玩扑克牌。