网友的两个句子，不能算错。

1. As a healthier lifestyle, bicycle has come back to people's life.

众所周知，普通可数名词在单数状态下，泛指加a，特指加the，若之前没有其他限定词，不能以零冠词用于句中。在科普英语或新闻英语中，有省略冠词的现象。“零冠词 + 可数名词单数”的用法，可以理解为“表示类别”，即“类指”。举例如下：

Bicycle can’t be compared with other means of transportation like car and train for speed and comfort.在速度和舒适度方面，自行车是无法和汽车、火车这样的交通工具相比的。（本句若在这几种交通工具前加上冠词，或者变成复数，反而显得啰嗦。）

It is widely acknowledged that computer and other machines have become an indispensable part of our society, which make our life and work more comfortable and less laborious.人们普遍认为计算机和其他设备已经成为我们社会必不可少的一部分。它们使我们的生活更舒适，减少了大量劳动。

2. Moon cake is atraditional food eaten by the Chinese during the Mid-Autumn Festical.

cake 和mooncake，都是“可变名词”（variable noun）。所谓“可变名词”，既可以是可数名词，也可以是不可数名词。本句应理解为不可数用法。

可数用法例句：

Did you make these cakes yourselves? 这些蛋糕是你们亲手做的吗?

I made a cake specially for you. 我特地为你做了个蛋糕。

Lucy, would you like another cake? 露西,你还想再要一块蛋糕吗?

不可数用法例句：

There isn't enough cake to go round.  没有足够的蛋糕分给每人吃。

Would you care for another piece of cake?  您再来一块蛋糕好吗?

Would you like some chocolate cake? 来点巧克力蛋糕怎么样?