阅读对话，判断正误，用“√”“×”表示。

A: Come here, Helen. What's that on the desk?    

B: It's a clock,

A: What's the time?                        

B: It's seven o'clock.

A: It's time to go to school.                  

B: OK. Let's go by bike.

(     )1. It's a clock on the desk. 

(     )2. It's six o'clock.

(     )3. It's time to go to school.    

(     )4. Let's go to school by bike.

实验室制取CO₂的发生装置应选用_______（填“固固加热型”或“固液常温型”），收集CO₂的方法：________________。