Do you know how often he ____（锻炼）?He is so strong.exercise用加单三吗
问题描述：
Do you know how often he ____（锻炼）?He is so strong.exercise用加单三吗
答
要加单三形式,答案为：exercises
从句中he是主语,是第三人称单数,且从句的时态明显是一般现在时,所以答案用exercises没错.The twins have no d_____from each other.difference 区别/差别/不同 当然你要用differences也可以。