①1cm5mm
②20mm
根据下列实验装置图,回答下列有关问题。
我会填
①更:共____画,第二画是 ____。
②雀:共____画,是____结构。
It was late. She opened the door ________ because she didn't want to wake up her grandma.
属于空气的主要成分,且能够用以抢救危重病人的气体是( )