The work is really very difficult,_it's very interesting.A.yetB.howeverc.stillD.at the same time

The work is really very difficult,_it's very interesting.A.yetB.howeverc.stillD.at the same time
The work is really very difficult,_it's very interesting.
A.yet
B.however
c.still
D.at the same time

The work is really very difficult,_it's very interesting.A.yetB.howeverc.stillD.at the same time
如果是D的话,就是工作真的很难,同时也很有趣,这个可能和个人说话习惯有关,或者这句话还有上下文,从字面意思上来理解的话D也是合理的