单项选择题 The pop stars promised to sing in the concert _______ free.onB. inC. withD. for

单项选择题 There are two computers in the office, but ________ is working.either of themB. neither of themC. none of themD. nothing of them

单项选择题 Our family education has a great effect ________ children.forB. withC. onD. about