高考高頻詞匯:tractor、tribe、undergo、upgrade、

tractor[?tr?kt?(r)]

【詞頻】★★☆☆☆

n. 拖拉機(jī)；牽引機(jī)

tribe[tra?b]

【詞頻】★★☆☆☆

n. 部落；部族；一幫；一伙

【派】tribal [?tra?bl] adj. 部落的；部族的

undergo[??nd??g??]

【詞頻】★★☆☆☆

v. 經(jīng)歷；接受；遭受；忍受

【例】v. 經(jīng)歷

（2011上海春）If you plan to start your career as a secretary, be aware that this job is undergoing tremendous changes.

【譯】如果你計劃開始當(dāng)秘書，那就要意識到這項工作正經(jīng)歷著巨變。

upgrade[??p?gre?d]

【詞頻】★★☆☆☆

v. 提升；使(機(jī)器、計算機(jī)系統(tǒng)等)升級