如图所示，理想变压器的原线圈接有交变电压U，副线圈接有光敏电阻R1（光敏电阻随光照强度增大而减小）、定值电阻R2．则（ ）
读东南亚地理简图，回答下列问题．
抓关键词是学习历史的方法之一。与“1956年”“制度初建”“20世纪中国的一次历史性巨变”等关键词相吻合的历史事件是（ ）
Today is Sunday. It is a sunny day. Mike and Paul are going to have a picnic in the park. There are many green trees. Near the gate，there is a lake. Some ducks are swimming on the lake.
Mike and Paul are going to have lunch at half past eleven. Then they are going to read some books under a big tree.
