单项选择题
A.useful
B.valuable
C.worth
D.good
单项选择题 If there were no examinations,we should have()at school.
单项选择题 We look forward to the day when the motorcar has been replaced by some less dangerous()of transport.
判断题 Constituents that can be substituted for one another without loss of grammaticality belong to the same syntatic category.()