衣藻、蓝藻、黑藻全部（ ） A．是原核生物 B．含有叶绿体 C．是自养生物 D．含有中心体
在长期放着煤的墙角处，地面和墙角壁面相当厚的一层染上了黑色，这说明( )A.分子是在不停地运动着 B.煤是由大量分子组成的C.分子
In order to prevent the disease ___________ to other districts, the authorized organization killed thousands and thousands of cows. A. extending B. spreading C. expandi
地名变更往往同当时的政治背景相关，苏联历史上曾经发生下列地名变更：（ ）①彼得格勒→列宁格勒 ②沙皇村→儿童村③
Many people find it difficult to do any activity for pure pleasure. I'm here to tell you about one of my favorite pleasures. It doesn't cost a thing and takes very little time. Best of all，you ca
Every morning Mr. Smith takes a ______ to his office. A.20 minutes’ walk B.20 minute’s walk C.20-minutes walk D.20-minute walk
用一个机械效率为70％的滑轮组，将重为2240N的重物提起，所用的拉力为800N，则滑轮组至少由（ ）组成A．1个定滑轮和1个动滑轮。B．2个定滑轮和2个
某学校地理兴趣小组于9月20日到福建省某无人海岛(119°E,26°N)进行野外考察活动。图4为该岛等高线地形图，读图回答6～8题。 6．图中①④两地的最大高
