以下是一些常用的英语四级作文万能句：

1. 开头句型：
- Nowadays, it is widely acknowledged that...
- With the rapid development of...
- In recent years, there has been a growing concern over...
- It is no doubt that...

2. 表达观点：
- From my perspective/viewpoint, I strongly believe that...
- Personally, I am of the opinion that...
- It is universally acknowledged that...
- There is a common saying that...

3. 表达原因：
- There are several reasons for this phenomenon.
- One of the main reasons is...
- Another contributing factor is...
- The primary reason can be attributed to...

4. 表达优缺点：
- On the one hand, it is undeniable that...
- On the other hand, it is worth noting that...
- However, there are also some drawbacks to...
- Despite the advantages, there are some disadvantages to...

5. 表达建议：
- In order to solve this problem, it is crucial that...
- It is high time that we took effective measures to...
- It is recommended that we should...
- To address this issue, it is advisable to...

6. 结尾句型：
- In conclusion, it is clear that...
- To sum up, we can draw the conclusion that...
- All in all, it can be said that...
- Taking all these factors into consideration, we can reach the conclusion that...

以上是一些常用的英语四级作文万能句，可以根据具体的写作内容和语境进行灵活运用。同时，为了提高作文的质量，还需注重词汇和语法的准确性，以及合理的段落结构和连贯的逻辑思路。