CO2气体保护焊时可能产生三种气孔，即______、______和______。
题型：填空题
问题：
CO2气体保护焊时可能产生三种气孔，即______、______和______。
题型：填空题
看图，判断句子对(√)错(×)。
( ) 1. There are four chairs in the picture.
( ) 2. The woman is eating.
( ) 3. The boy is happy.
( ) 4. There is no fruit on the table.
( ) 5. We can see a dog on the chair.
( ) 6. There is a hamburger on the table.
