被誉为“世界建桥史上的一个奇迹”，并被后人称赞为“百尺长虹横水面，一弯新月出云霄”的桥是指 [ ]
A、灞桥
B、卢沟桥
C、赵州桥
D、泸定桥
答案：C
Children are ______ to meet with setbacks (挫折) as they grow up, so their parents don’t have to worry about it.
A．possible
B．due
C．necessary
D．bound
什么是离心分离因素
