A：4
B：－
C：
D：
Kate isn't happy because she lost her pet. Let's go to cheer her up.
— Excuse me, Dad, but I'm going to the club to meet my friends in the football team.
— Ok. _____.
敲打铜锣，因锣面振动而发出声音，而在月球上由于没有空气，宇航员即使再用力敲打，他也不能直接听到锣声，这是因为 ____不能传声．
的绝对值等于（ ）
