错了呗.
答案应该是is standing,is sitting.第一句交代了时间,now.应该用进行时.
写书的人他也不是神仙啊.他自己认为是正确的,其实不然.
按答案
Our teacher doesn't stand up right now.
这句话,怎么理解?显然是不通的.
而后文,She is sitting on the conner of her desk.
她正坐在她桌子的角上.这老师也够淘气的了.暂且不提,这句话,用了进行时,根据是什么?显然根据前句的right now.
第一句也应该用进行时.
涉及到现在字眼的句子中,谓语动词用一般现在时的动词,是want,need,这样的,比如.
She doesn't want to stand up now.
She needs to stand up now.
stand,做位于动词,时间是now,必须用进行时.