Liu Ying的英语不如她妹妹的好.[翻译成英文]

Liu Ying's english is poorer than her younger sisiter's.

Liu Ying's english ability is lower than her younger sisiter's.

Liu Ying's English is not as good as her younger sister's

Liu Ying's english is not better than her sister's

....
Liu Ying's younger sister speaks English better than Liu Ying.
Liu Ying cannot speak English as well as her younger sister.

听我的：
liu Ying is not as good at English as her sister.
Liu Ying's English is not as good as her sister's.
Liu Ying does speak as good English as her sister does.

Liu ying's English skill are not as well as hen sister's.