41.there is an upward trend in the number of...

...数字呈上升趋势。

42.a considerable increase/decrease occurred from...to...

...到...发生急剧上升。

43.from...to...the rate of decrease slow down.

从...到...，下降速率减慢。

44.from this year on，there was a gradual declinel reduction in the...,reaching a figure of...

从这年起，...逐渐下降至...

45.be similar to...

与...相似

46.be the same as...

与...相同

47.there are a lot similarities/differences between...and...

...与...之间有许多相似(不同)之处

48.a has something in common with b

a于b有共同之处。

49.the difference between a and b lies in...

a与b之间的差别在于...

50...(year)witnessed/saw a sharp rise in...

...年...急剧上升

当然并不是背熟了这些句子就一定会得高分，图表作文的篇章布局和逻辑结构也很重要。所以如果条件允许，建议大家参加雅思写作辅导班，有经验的老师会教你如何写，并帮你修改，这样的话提高就会很快。