我国北方地区近年来沙尘天气日数呈增长趋势。沙尘天气在气象学上按强度差异划分为浮尘、扬沙和沙尘暴三个等级。扬沙是由于本地或附近尘沙被
— How did you get to school this morning? — By taxi. I didn’t catch the school bus ______ I had to take a taxi. A. so
Sandy: How was your vacation in America? Linda: It couldn’t be worse! I don’t want to talk about it! A.evenB.leastC.neverD.then
如图为从蛙后肢上分离出其坐骨神经的示意图,如果在电极a的左侧给一适当的刺激,则 A.ab(膜外侧)之间会产生电流,方向为a→b B.相应的膜内侧
下列工业中心中,位于珠江三角洲工业基地的是( ) A、广州 B、武汉 C、成都 D、兰州