现在进行时的被动语态
定义：现在进行时的被动语态表示此时此刻某事正在被做.
例如：
The sports meeting is being held in our school.
我校正在举行运动会.
Another bridge is being built over the Changjiang River.
长江上正在修建另一座大桥.
构成：be + being+过去分词
例如：
A number of Dongfeng trucks are being shipped abroad.
一批东风卡车正被运往国外.
用法：
1）“be being done” 中的动词be应随主语(sing./ pl.)作相应的变化.
2）将现在进行时的主动语态变为现在进行时的被动语态的关键是：把be doing变为be being done.
例1.The students are cleaning the classroom now.
→The classroom is being cleaned now.
现在学生们正在打扫教室.(are cleaning变为is being cleaned)
例2.The boy is counting some eggs.
→Some eggs are being counted.
那男孩正在数蛋.(is counting 变为 are being counted)
你也可以给他们对比讲一下：现在完成时
