— Where is my pen ? Have you seen ____?— Oh, sorry. I have taken ____ by mistake.
Listen! I hear someone________ the door.
—I’m going to Hainan with my aunt for my holiday after the exam.—_______.
—What do you think of Liu Huan?—Oh, he is my favorite singer. I think no one can sing________.
Everybody should remember it is not _________ to swim in the river alone.
Some students are so ______ that they often make mistakes in their homework.