It is believed that stars originate as condensations 1 interstellar matter. In certain instances a protostar will form, slowly contracting under its own gravity, part of the energy from this contraction being radiated, the remainder heating up the core. This stage may last several million years. Finally, the core becomes hot enough for thermonuclear reactions 2 sustained, and stops contracting. Eventually the star 3 ceases contracting and radiates entirely by the thermonuclear conversion of hydrogen into helium; it is then 4 to be in its main sequence. Later 5 , when all of the hydrogen in the core has been converted to helium, the star will expand for approximately 200 million years until it becomes a red giant. Then the star will usually contract once again, converting its helium core into carbon, and end its life as a white dwarf star. 1. (A) out of (B) into (C) up to (D) upon 2. (A) being (B) to be (C) be (D) will be 3. (A) as a whole (B) in between (C) once again (D) at the same time 4. (A) come (B) gone (C) said (D) told 5. (A) in (B) off (C) out (D) on 解析： 1. 本題考正確之複合介系詞。由 that 子句中的動詞 "originate"( 起始 ) 可知，最適合之選項應為 (A) out of 。 "stars originate...out of interstellar matter" 的意思是：星球起源自星際間的物質。其他選項皆與題意不符。 2. 本題考正確之動詞形式。依文法，在副詞 "enough"( 足夠 ) 之後應使用動詞之不定詞形式。正確答案為 (B) to be 。【注意， "to be sustained( 維持 )" 為「被動式」。】 其他選項之動詞形式皆不合文法。 3. 本題考正確片語之使用。依前後文意，正確選項應是 (A) as a whole 。 "Eventually the star as a whole ceases contracting" 指的是：最後整個星球停止收縮。選項 (B) in between ( 在 ... 之間 ) 與題意無關；選項 (C) once again ( 再一次 ) 與前後文意不符；選項 (D) at the same time ( 在同一時間 ) 亦與句意不搭軋。 4. 本題須選出正確之過去分詞。由本子句之主詞 "it"( 指 "the star") 及其後之 be 動詞 "is" 來判斷，這是個「被動」之句型。由於選項 (A) come 與 (B) gone 皆屬「不及物動詞」，理論上是沒有被動式的，因此可先排除。選項 (D) told 指「告訴」，而星球不應作為「被告訴」的對象，故 (D) 亦不可選。本題正確答案為 (C) said 。 "it is...said..." 是「它 ( 該星球 ) 被說成是 ... 」之意。 5. 本題須選出正確之介副詞。由空格前的 "Later" 即可知，本題應選 (D) on 。 "later on" 指「以後」、「之後」。其他選項雖皆可作介副詞，但都無法與 later 做聯結。 | 
