成年人应该知道如何帮助孩子们在智力上发展。

单项选择题By walking to and from school, children can learn ______.

单项选择题2（）。

A.wanted 
B.did 
C.got 
D.played

问答题公司把亏损归咎于最近的经济发展趋势上。

问答题约翰跳进了河，我也跳了进去。

单项选择题What does the author think is the main difference between a punctual person and an unpunctual person（）。

A. A punctual person does everything ahead of time while an unpunctual person does everything behind schedule.
B. A punctual person does everything at the right time while an unpunctual person seldom does anything at the correct time.
C. A punctual person has a lot of appointments while an unpunctual person has few appointments.
D. A punctual person has much time to do everything while an unpunctual person has little time to do anything.