I wonder if the prof took attendance¹ already. 哎呀呀，不知道教授是不是已经点名了!

　　prof＝professor，take attendance 点名。

God, I only missed two classes and I＇m already out of it. 天哪! 我才误了两节课，可是已经跟不上了!

　　be out of it 是跟不上的意思，所以得 catch up with them ASAP

Hey, I got the whole info from the upperclassman. 喂，我已经从学长那里拿到所有的资料了。

　　info＝information， upperclassman 学长，也可能学长为seniors或 older guys

That guy is a tough nut. I guess this class is a bear！这老师比较难搞定，我估计这门功课悬了!

　　难缠的老师称为 tough nut，bear表示很难的科目。

I struggle for words when asked a sudden question. 突然被问到时我都得措词半天。

　　struggle for words 难以回答