____ before we depart the day after tomorrow, we should have a wonderful dinner party.
A、HadtheyarrivedD
【句意】如果他們能在我們后天離開之前趕到的話，我們就舉行一次盛大的宴會。
【難點】表示將來不可能發生的事實，常用虛擬語氣，主句的謂語為should+動詞原形(適用于第一人稱主語)或would,could,might+動詞原形(適用于其余人稱主語);而條件句的謂語應該用should+動詞原形，wereto+動詞原形或直接用動詞的過去時(如be改用were)。
Unless all the members agree to __8__to the plan there may be further development in the course of action.
______ they are twin sisters, they don ’t look like each other.
People in some areas don’t have to pay for their ______.
It’snecessary_________usallto________
I ’d like to have a long holiday, but I’m really too busy to _____ the time.
