第八章 时态和语态第一节 时 态

一、一般现在时

表示现在的状态，习惯或普通的、客观的现象或真理时，应使用一般现在时。

Certain layers of the atmosphere have special names .

  1. which indicated their character properties.

  2. whose characteristic properties are indicating

  3. what characterize their indicated properties

  4. that indicate their characteristic properties

D)为正确答案。本句表述的亦是自然界中的客观现象，主从句都应用一般现在时，故 A）和 B）都不对，C）不合语法，所以只有 D）正确。Igneous（火成的）rock from the cooling and solidifi-cation of melten（熔化的）matter from the Earth's interior.

A)being originated B)have originated C)originates D)originating

C)对，理由同上。