The college has developed an on-line system ________students can choose their own professors.

Why do you make me do so? —— I am sorry that you＿＿＿＿＿＿＿＿do such a thing.

Didn’tever occurto you what the source of this saying I just quoted is

____ is your schoolbag—It’s green.

My father has a habit of jogging _____ the Jinchuan River for an hour in the morning.