Periodic

用法：①ADJ. Periodic events or situations happen occasionally， at fairly regular intervals.

例句：They especially emphasized the need for natural， serene settings where hurried urban dwellers could periodically escape from the city. (2002-01)

例句：This periodic extinction might be due to intersection of the Earth’ s orbit with a cloud of comets， but this theory is purely speculative. (2002-08)

例句：Periodically， molten material wells out of the Earth’s interior to invade the surface layers or to flow onto the surface itself. This material cools into a wide variety of igneous rocks. (1999-01)

例句：The woolly mammoth， along- haired rhinoceros， and other mammals have been periodically exposed in the tundra of Siberia， the hair and red flesh still frozen in cold storage.(1997-12)

例句：Periodic exhibitions of the members’ paintings also included works by noted English artists of the day， borrowed from embryonic private collections in the city. (1999-10)

Peripheral

用法：① ADJ. A peripheral activity or issue is one which is not very important compared with other activities or issues.

例句：Over 100 designated areas exist around the periphery of the Carbbean Sea.(2000-01)

②ADJ. Peripheral areas of land are ones which are on the edge of a larger area.

例句：These are the central nervous system (the nerve cord mentions above)， consisting of the brain and spinal cord， and the peripheral nervous system， consisting of the cranial， spinal， and peripheral nerves， together with their motor and sensory endings.

托福作文寫作誤區(qū)：字數(shù)并非越多越好

單純認為“字數(shù)越多越好”的時候，這里是有一定的道理的。因為如果你的字數(shù)越多，那么就越能更好的闡明自己的觀點，但是很多考生特別喜歡將這種思路一直用。要知道，托福作文在350字—450字就很好了，這個范圍內(nèi)基本上不會對你的分數(shù)產(chǎn)生任何負面的影響了。

當然還會馬上有人問，如果我的作文字數(shù)超過了500字呢?說真的，如果你能有寫500字的能力，那么為什么不省下來一些時間，來自己檢查一下這篇作文呢?因為當作文達到500字的時候，已經(jīng)高于托福所要求的字數(shù)了，再寫多一點已經(jīng)不會提升你的分數(shù)，當然也不會使你的分數(shù)降低。因此，這個時候不如好好修改一下已經(jīng)寫過的文章，或者把寫過的文章好好潤潤色。(例如：加入一些強調(diào)句式或者倒裝句，這樣會使自己的文章看上去更有生氣。)因此，我們只要能寫到350字以上，我們在字數(shù)這一點上基本就完成了任務(wù)，完全沒有一定讓自己的作文字數(shù)超過500字，要知道“越多越好”也不一定是好的。