It looks like a precisely engineered jigsaw puzzle, each branch growing just perfectly so it almost, 11 , touches the neighboring tree.
答案：(C) but not quite
almost, but not quite, touches 意為「幾乎碰到、但就是差那麼一點」，正是樹冠羞避現象的關鍵；in no time（立刻）、by all means（當然可以）、and pretty much（差不多）語意都不合。
句子裡已經有 almost（幾乎），你會覺得再補一句是多餘的，於是把 but not quite 排除。事實上 almost, but not quite 是一組固定的強調說法：almost 只說了「很接近」，but not quite 才點出「就是沒到」——中文是「幾乎，卻又差那麼一點」。
空格夾在兩個逗號之間，是插入語；將它移除後，句子 each branch growing just perfectly so it almost touches the neighboring tree 仍然完整，可見這一格補的是對 almost 的進一步說明。本文對枝條究竟碰到與否，有三處明確的敘述，可逐一核對：第一句 a network of cracks formed by gaps between the outermost edges of tree branches（樹枝末梢之間的縫隙所形成的網狀裂紋）；第三段 trees maintain 「shyness gaps」—spaces large enough to prevent them from touching their neighbors（樹木維持著羞避縫隙，其寬度足以避免彼此接觸）；末段 by having branches that do not touch those of their neighbors（藉由枝條不與鄰樹接觸）。三處都直言並未接觸，插入語必須把 almost 修正為「終究沒有碰到」，故應填 but not quite。凡是兩個逗號之間的插入語，判斷步驟相同：先將插入語移除，確認主句的意思，再回到全文找出與該點直接相關的敘述逐一核對。not quite 屬部分否定，如 I don't quite understand.、It's not quite ready.，quite 前加 not，表示尚未完全達到。
and pretty much 意為「而且差不多」，填入後句意成為枝條實際上已經碰到鄰樹，與上述三處敘述牴觸，且與 almost 語意重複；in no time 意為「立刻、很快」；by all means 意為「當然可以、務必」，用於答應對方的請求。
almost, but not quite（幾乎，卻差那麼一點）、not quite（不完全）、not exactly（不盡然）、in no time（立刻）、by all means（當然可以）。
In certain forests, when you look up you will see a network of cracks formed by gaps between the outermost edges of tree branches. It looks like a precisely engineered jigsaw puzzle, each branch growing just perfectly so it almost, 11 , touches the neighboring tree. This beautiful phenomenon is called crown shyness.
Scientists have been discussing crown shyness since the 1920s, proposing 12 explanations for the phenomenon. Some researchers point out that as trees often grow close together, treetops can easily collide and break when swayed by the wind. In order to protect their branches from breakage, trees maintain "shyness gaps"—spaces large enough to prevent them from touching their neighbors.
Other scientists suggest that plants, like animals, 13 resources—nutrients, water, space, and light. In forested areas with thick tree crowns, there is intense struggle for these resources. Gaps in the treetops resulting from crown shyness may allow trees to increase their 14 light and enhance photosynthesis. Additionally, by having branches that do not touch those of their neighbors, trees may be able to limit the spread of leaf-eating insects, and potentially also the transmission of diseases from tree to tree.
15 decades of investigation, there is no consensus on exactly what causes the beautiful and mysterious phenomenon of crown shyness.