重點(diǎn)講解：
1. stumble upon 意外發(fā)現(xiàn)；偶然看見；
例句：It had surprised him to stumble upon a dirty, forgotten place like that in a bank that was always so tidy.
在像銀行這樣一個(gè)素來十分潔凈的地方，竟會(huì)撞見一處骯臟的，被人遺忘的死角，使他感到十分驚訝Go4!A5bv3+J@6TW@d4B。
2. be known as 稱為；叫做；
例句：This process is known as adaptation.
這個(gè)過程即所謂適應(yīng)hZ.Ia)(ykEpJbQv。
3. hold up （論點(diǎn)、理論等）經(jīng)受得住檢驗(yàn)；
例句：I'm not sure if the argument holds up, but it's stimulating.
我不能肯定該論點(diǎn)是否經(jīng)得起檢驗(yàn)，但它很有新意zNjpzQ5]|8|Bu-qA9@_。
4. in theory 從理論上說；照理說；
例句：That may be reasonable in theory but it sounds fanciful in practice.
從理論上看這是說得過去的，可實(shí)際上卻有點(diǎn)異想天開UIh&NvCx[D。