黄河中下游含沙量大的主要原因是( )
A:注入的支流众多
B:降水量大 位于湿润区
C:水流速度快
D:流经黄土高原区
当北半球夏至日时,出现极昼现象是地区是( )
I can sing. What you?
Sara didn't feel well this morning. She decided ________ to the park with her sister.
⑤集体力量取决于成员的数量