4.that指人/物,作主语或宾语 (作宾语可省略) a plane is a machine. It can fly. a plane is a machine that can fly. He is the man. I told you about him He is the man (that/who/whom)I told you about4. that 指人/物，作主语或宾语 (作宾语可省略） A plane is a machine. It can fly. A plane is a machine that can fly. He is the man. I told you about him. He is the man (that/who/whom) I told you about