对话填词。

A: What's this?

B: It's a photo 1_______ my sister.

A: You have a nice sister.

B: Thanks.

A: Where 2_______ your sister work?

B: She 3_______ at a hospital.

A: What 4_______ she do?

B: She is a doctor. What 5_______ your sister?

A: She is a doctor, 6_______.

B: Does she like the job?

A: No. she 7_______ it's difficult.

B: What does she want to 8_______?

A: Sorry, I don't know.

关于二氧化碳气体保护焊，以下说法错误的是（）。

A、受到外加的热源时，气瓶有造成爆炸的危险

B、气瓶应小心轻放，竖立固定

C、在气体快用尽时，可以将气瓶倾倒使用