when I ____ there, I found that everything ____ ready

问题描述:

when I ____ there, I found that everything ____ ready
A reached;was
B got to;were
C arrived at;was
D arrived;were
回答并说明理由.谢谢

CD都不可能,因为arrive后面要加at/in.
又因为I found that everything ____ ready ,里面是everything,单数,要用was