1、毫无疑问......

　　There is no doubt (that)...

　　例句：There is no doubt that complacency is the enemy of study.

　　毫无疑问，学习的敌人是自己的满足。

　　2、根据我个人经验......

　　According to my personal experience, ...= Based on my personal experience, ...

　　例句：According to my personal experience, true mastery of any skill takes a lifetime.

　　根据我个人经验，对任何技能的掌握都需要一生的刻苦操练。

　　3、随着人口的增加......

　　With the increase/growth of the population, ...

　　随着科技的进步, ......

　　With the advance of science and technology, ...

　　With the rapid development of China's economy, a lot of social problems have come to pass.

　　虽然中国经济的快速发展，很多社会问题也随之产生了。

　　4、......是必要的

　　It is necessary that ...

　　...是重要的

　　It is important/essential that......

　　...是适当的

　　It is proper that......

　　...是紧急的

　　It is urgent that ......

　　5、.......的主要理由是......

　　The main reason why ... is (that)

　　例句：The main reason why the juveniles commit crimes is that social environment is becoming worse.

　　青少年犯罪的主要理由是社会环境日一败坏。

　　6、俗语说得好...

　　Well goes an old saying,"…"= As an old saying goes(runs, says), "…"= An old saying goes, "…"

　　例句：As an old saying goes, "don't put off till tomorrow what should be done today."

　　俗话说的好，今日事，今日毕。

　　7、据说......

　　It is said (that)...

　　一般认为......

　　It is thought (that)...

　　大家都知道......

　　It is known (that)...

　　据报道......

　　It is reported (that)

　　预料......

　　It is expected (that)...

　　估计......

　　It is estimated (that)...

　　相信......

　　It is believed (that)...

　　例句：It is believed (that) nothing is difficult to the man who will try.

　　相信世上无难事，只要肯登攀。