A:①②
B:②③
C:①③
D:③④
下列说法正确的有( )。①.在同圆或等圆中能够完全重合的弧叫等弧;②.在同一平面内,圆是到定点距离等于定长的点的集合;③.度数相等的弧叫做等弧;④.优弧大于劣弧;⑤.直角三角形的外心是其斜边中点。
____应该 如:We are supposed to stop smoking. 我们应该停止吸烟。
知识拓展 表示"应该"的词有:should, ought to,be supposed to
—We all went to the park except you last weekend. Why didn't you come?
—Because I the park twice.