按照国外对个人对环境保护了解层次划分的标准肤浅的生态学层次是在第（）级
A.一
B.二
C.三
D.四
参考答案：A
Living in the central Australian desert has its problems,______ obtaining water is not the least.
A．for which
B．to which
C．of which
D．in which
同国际市场的习惯做法一样，我国海运货物基本险的保险期限一般也采用（）的原则。
A、“门到门”
B、“桌到桌”
C、“仓至仓”
D、“港到港”
