鉴别菌痢和阿米巴痢疾最可靠的依据是（） A.潜伏期的长短 B.毒血症的轻重 C.大便

阅读短文，从方框中选择适当的动词，并用其适当形式填空。有的需要加助动词或不定式符号。（每词限用一次）

work   regard   help   buy   study

All of my students think I’m a good teacher. I 小题1:_________ in the school since 1999. I am always nice to my students. I often 小题2:___________ them with their school work. So I 小题3:_________ as their best friend. They love me very much and they often do something nice for me. One day before Teachers’ Day, some of my students 小题4:__________ me some presents. When they gave me the presents, they said “Thank you for teaching us so well and we小题5:__________ harder than before.” How nice my students are!