Ben goes to work ________ and his sister goes to work ________.
A：by car; on her bike
B：by a car; on her bike
C：by cars; by bikes
D：by his car; by bike
1000千克青菜，早晨测得它的含水率是97%，下午测得它的含水率是95%，那么这些菜重量减少了____ 千克．
