下列哪种方法是绝育措施()
A.药物避孕
B.男用避孕套
C.体外排精
D.安全期避孕
E.双侧输精管结扎及粘堵术
参考答案:E
In the last few years thousands of films ________ all over the world.
A.have produced
B.have been produced
C.are producing
D.are being produced
无线网络优化的实质是什么?