【正确答案】 D

【答案解析】[试题分析] 词组含义理解。
[详细解答] such as为复合连接词，引出同位语DNA and RNA，对前面的some complex cell chemicals起列举作用，可译为“例如”。as though似乎，as that像那一样，as such确切而言，完全地，例：I didn't have a nervous breakdown as such，it was more a reaction to overwork．我不是真的得了精神崩溃，那只是工作过度的反应。such as这两个单词既可分开用，也可合起来用。Such accommodation as she could find was expensive．她所找的住处很贵。There are many people in the hall，such as…有许多人在大厅里，例如……