I am especially proud of it, not only because it has survived several severe winters,but because it occasionally produces luscious peaches. During the summer, I noticedthat the leaves of the tree were beginning to wither. Clusters of tiny insects calledaphids were to be found on the underside of the leaves.

　　16.I am especially proud of it, not only because it has survived several severewinters, but because it occasionally produces luscious peaches.

　　我为这棵树感到特别自豪，不仅因为它度过了几个寒冬终于活了下来，而且还因为它有时结出些甘甜的桃子来。

　　语言点:句子结构分析:两个because的作用都是引导原因状语从句。

　　17.During the summer, I noticed that the leaves of the tree were beginning to wither.

　　到了夏天，我发现树叶开始枯萎。

　　语言点:句子结构分析:that引导宾语从句。

　　18.Clusters of tiny insects called aphids were to be found on the underside of theleaves.

　　结果在树叶背面找到成串的叫作蚜虫小虫子。

　　语言点:句子结构分析:called aphides作后置定语。be to do sth.表示事情必然要发生。