6.The latter may commit crimes _lack of adequate parental control. All theories， however， are tentative and are subject to criticism.
［A］ on
［B］ in
［C］ for
［D］ with
解析：for 可以作為前置詞，表示原因。lack of adequate parental control（缺乏父母管教）與前文 commit crimes 存在原因關(guān)系，故選［C］。
7.The continental ice sheet is more than two miles high at its center; thus， the air over the Antarctic is far more refrigerated than it is over the Arctic regions. This cold air cascades off the land with such that it makes the nearby seas the stormiest in the world and renders unlivable those regions whose counterparts at the opposite end of the globe are inhabited.
［A］ force
［B］ roughness
［C］ influence
［D］ coldness
解析：cascade 本意指“瀑布般地流下，瀉下”，這里就是指冷空氣來(lái)勢(shì)兇猛，力量很大，所以正確答案是 force。
8.But at the beginning of this century， the tango was refined， so that it lost its erotic features. It was preformed in fashionable casino ballrooms. The tango， in its sophisticated European ， became popular in England and in the USA.
［A］ shape
［B］ form
［C］ format
［D］ contour
解析：根 據(jù)上下 文辨別 詞意： ［A］ shape“外形 ，形狀 ”; ［B］ form“形 式，種 類”;［C］format“樣式”;［D］ contour“輪廓，外形”。顯然，正確的選項(xiàng)是［B］。
［A］ on
［B］ in
［C］ for
［D］ with
解析：for 可以作為前置詞，表示原因。lack of adequate parental control（缺乏父母管教）與前文 commit crimes 存在原因關(guān)系，故選［C］。
7.The continental ice sheet is more than two miles high at its center; thus， the air over the Antarctic is far more refrigerated than it is over the Arctic regions. This cold air cascades off the land with such that it makes the nearby seas the stormiest in the world and renders unlivable those regions whose counterparts at the opposite end of the globe are inhabited.
［A］ force
［B］ roughness
［C］ influence
［D］ coldness
解析：cascade 本意指“瀑布般地流下，瀉下”，這里就是指冷空氣來(lái)勢(shì)兇猛，力量很大，所以正確答案是 force。
8.But at the beginning of this century， the tango was refined， so that it lost its erotic features. It was preformed in fashionable casino ballrooms. The tango， in its sophisticated European ， became popular in England and in the USA.
［A］ shape
［B］ form
［C］ format
［D］ contour
解析：根 據(jù)上下 文辨別 詞意： ［A］ shape“外形 ，形狀 ”; ［B］ form“形 式，種 類”;［C］format“樣式”;［D］ contour“輪廓，外形”。顯然，正確的選項(xiàng)是［B］。