2014年6月英语四级作文真题附范文(第2套):A Beautiful City in China

语句间的衔接成分用的不错，同时文章中的过程性词汇很丰富；作者在句法层面做的很棒；文章高级词汇使用熟练，词汇表达较为丰富。

The results in Table 5 show that both the conversion of SO and the yield of SC increased firstly (entries 1–3) and then almost kept constant with elevating temperature (entries 4,5). It can also be seen that the selectivity to SC was almost independent on temperature, which changed in a small range from 83.5 to 89.1%. The reaction of SO with CO2 promoted by elevating temperature initially is consistent with our previous work [25] while the change tendency in selectivity is not. The selectivity to SC was relatively low whether at lower or higher temperature in our previous work due to side reactions of Meinwald rearrangement and copolymerization, respectively. In this work, the total yield of main by-products including phenylacetaldehyde and acetophenone changed in a small range from 1.1 to 0.7%. It was far lower than that obtained in the presence of ZnBr2 [25], in which around 4.9% total yield was obtained, further confirming that Meinwald rearrangement of SC was promoted by Lewis acid while retarded in the presence of Cu(acac)2.