【坏处1：健康，免疫力，记忆力，睡眠】首先，xxx 严重威胁到了我们的身体健康。很多研究表明，xxx 对人体免疫力，记忆力，睡眠都有极大的负面影响。

1. A. First, xxx poses a huge threat to our health. Numerous studies have shown/suggested that xxx exerts an extremely/tremendously negative effect on people’s immune system as well as their memory and sleeping.
2. B. First, xxx poses a huge threat to our health. Numerous studies has shown/suggested that xxx exerts an extremely/tremendously negative effect on people’s immune system as well as their memory and sleeping.