下列各句均有一处错误,请找出并改正 1. - Whose pen is this ? - It's her . A                B      C   D 2. They don't have any classes in Saturdays . A             B             C      D 3. He enjoys swiming in the river in summer. A          B     C              D 4. The twins don't do their housework on July. A          B          C         D 5. What do you do in the weekend? A    B         C  D (     )__________ (     )__________ (     )__________ (     )__________ (     )__________