1. ______ you were busy, I wouldn’t have bothered you with my questions.
A. If I realized B. Had I realized
C. Did I have realized that D. As I realized

2. There are many kinds of metals, ______.
A. each having its special properties B. having its special properties
C. one has its special properties D. each has its special properties

3. Both Lily and Lucy ______ to the party yesterday.
　 A. invited B. was invited
C. had invited D. were invited

1. 本題答案是B。
典型的表示與過(guò)去事實(shí)相反的虛擬語(yǔ)氣句型，條件狀語(yǔ)從句用if+主語(yǔ)+過(guò)去分詞，主句用：主語(yǔ)+ would (not)/should（not）+過(guò)去分詞，當(dāng)省略if 時(shí)，條件從句中的had 提前。故答案為B。

2. 本題答案是A。
本句考察獨(dú)立主格結(jié)構(gòu)。B沒(méi)有主語(yǔ)；逗號(hào)不能連接兩個(gè)獨(dú)立完整的句子，因此排除C，D；只能選A。句意為“金屬有很多種，每一種都有它的特性�！惫蚀鸢笧锳。

3. 本題答案是D。
由both … and … 連接兩個(gè)單數(shù)名詞作主語(yǔ)時(shí)，謂語(yǔ)動(dòng)詞用復(fù)數(shù)形式。故答案為D。