it's eight o'clock already. Jack be here by now.

題目：

it's eight o'clock already. Jack be here by now.
--It's eight o'clock already. Jack_______be here by now.
--Oh, he told me that he was going to see his dentist and wouldn't be back until ten.
A. must B. can C. should D. could
答案: should
求解釋

解答：

should be here by now ,翻譯爲「應該在這裡了」 比較合適,在這兒,should用來表推測、判斷.「已經8點了」 故他推測,Jack 現在應該在這裡了.must 是表肯定語氣,且比較加強語氣的,一般不會在此類題目中選擇此項,除非碰到對話雙方兩人語氣較強硬、惡劣,例如：you must clean up the house in the morning! 你今天上午一定要把屋子收拾好! 帶有命令的語氣,不完成就會怎麼怎麼樣.can 是表推測程度較大的,Jack can be here any moment,Jack 隨時都可能出現在這兒,他會來,但說話人並不知道他什麼時候來,這裡翻譯作「能」比較合適.should也表推測,但它的肯定程度大於can,即,按照常識,Jack現在該出現了,說話人知道Jack大概會在什麼時間到這裡,翻譯作「應該」.could是can更委婉的表達方法,當然它是can的過去式,但本題不涉及時態問題,因此其解釋與使用can相同.故本題最終答案爲should.這麼解釋滿意麼?