This is because they had no natural enemies until the arrival of humans and therefore did not need to develop flying wings.
這是因為人類到達(dá)這里之前，這些鳥沒有天敵，因此，它們不需要發(fā)育飛行的翅膀。
高三英語課文
Unit 19 New Zealand
?? 句中詞匯解析
從本句中提取的重要詞匯
conj. 因為;
?? cause, cuse 表原因,目的;司法程序,訴訟
"He was arrested because of his political affiliation."
他因所屬政黨的關(guān)系而被捕。
近義：since, whereas, for, forasmuchas
adj. 自然的;物質(zhì)的;天生的;不做作的;
n. 自然的事情;（生來的）白癡;[樂]（風(fēng)琴等的）白鍵;
?? natur=nature自然+al...的 →自然（界）的
"She showed a natural aptitude for the work."
她表現(xiàn)出了做這工作的天賦。
近義：inherent, lifelike, unaffected, native, raw, unprocessed
反義：hypothetical, illusional, illusionary, illusive, illusory, imaginative
n. 到達(dá)，抵達(dá);出現(xiàn)，登場;新生嬰兒;到達(dá)者;
?? arriv=arrive到達(dá)+al表示人 →到達(dá)者
"Shortly after my arrival at the school, I was befriended by an older girl."
我到學(xué)校后不久便得到了一位年齡較大的女孩友善對待。
近義：appearance, appearing, imminence, approach, approaching, assistance
反義：parting, withdrawment, departure, egress, exit, exodus
adv. 因此;所以;故;乃;
?? there這樣+fore無實義 → 因此，所以
"He lost his health, and therefore his difficulties increased."
他身體虛弱, 因此更增加了他的困難.
近義：hence, hencewith, hereupon, appropriately, avaunt, properly
vi. 發(fā)展;生長;形成;發(fā)達(dá) ;
vt. 發(fā)展;開發(fā);研制;沖洗（膠片）;
?? de相反+velop蓋上→不阻止，不掩蓋→發(fā)展，形成，開發(fā)
"to develop a strategy for dealing with unemployment"
制訂解決失業(yè)問題的對策
近義：urbanize, cultivate, evolve, expand, fabricate, amplify
反義：accomplish, climax, complete, crown, finalize, stanch