【题目】The letters for the boss___________ on his desk but he didn't read them until 3 days later.
A.were put
B.was put
C.put
D.has put

【答案】A
【解析】句意：给老板的那些信放在他的办公桌上，但是直到三天以后他才读了那些信。letter“信件”和put“放”之间是被动的关系，所以排除C和D，然后因为letters是复数，所以选择A选项。