He may fall behind other students when he come back?

He may fall behind other students when he come back? he may fall behind ___ students when he comes back.A other B ___ ___that he may fall behind the other students. When he will come back tell me when he will come back when _ he _ back.(come) When will he be back when will he come back When he came bac I don't know when he _(come)back.when he _(come)back,I will when will he come back还是when he will come back They are afraid that he may fall behind others.的意思 He tried _____(not fall) behind others. He wanted to know when they back(come)