The zoo keeper is worried because the number of visitors ________ smaller and smaller. A．become B．became C．is becoming D．have become
三杯两盏淡酒，_______________________! (李清照《声声慢》)
Hawaii has planned to be the first U.S. state to roll out（正式推出）electric car stations statewide --- a move towards weaning the islands off oil. Hawaii, which is far away from the U.S. mainl
A $1000 ____will be offered to anyone who helps to return the lost jewel . A . fare B . reward C . fee D . value
下列物质一定属于同系物的是 A．①和② B．④和⑥ C．⑤和⑦ D．④和⑧
下图表示某生物膜的部分结构，图中A、B、C、D表示某些物质，a、b、c、d表示物质跨膜运输方式。下列说法错误的是
当居民消费不足，需求下降的时候，商品供求关系改变，产品价格下降，厂商生产萎缩，投资下降，从而引发经济衰退。政府为避免此情况出现应该采
为了转播火箭发射的实况，在发射场建立了发射台用于发射广播与电视信号.已知传输无线电广播所用的电磁波波长为550 m，而传输电视信号所用的电磁
