Simon thought his puter was broken his little brother pointed out that he had forgotten to turn it on.
A. until
B. since
C. after
D. because
网友回答
(答案→)A. until
B. since
C. after
D. because
解析：本题考查连词。根据句意他一直以为电脑坏了，直到他弟弟告诉他忘记开机了；not...until...意为“直到……才”。