YOU SAID:

my sister thinks she freezes but she acts like a car

INTO JAPANESE

妹はフリーズすると思うが、車のように振る舞う

BACK INTO ENGLISH

I think my sister freezes, but behaves like a car

INTO JAPANESE

私の妹はフリーズすると思いますが、車のように振る舞います

BACK INTO ENGLISH

I think my sister freezes, but behaves like a car