only then是不是代表虚拟语气

D,only then放在句首,句子要倒装,所以排除AB,后面有was可以知道时态是过去式,而且前面的then也是标志,所以用did.

only 的用法
.only位于句首修饰壮语要倒装
只有倒那时我才将会有机会实现我的梦想.
will 是谓语的一部分因倒装提前了.再如
only in this way can you learn english well
是only引起的倒装句,will 是助动词,如果这个句子正过来说就是 I will have a chance of
achieving my dream only then
在句首的only如果后面跟了副词、介词短语或从句等状语,则主句用倒装结构.如only后跟
的是主语,就不用倒装结构了.例如：
Only when the war was over in 1918 was he able to get back to work．
Only in this way can you learn English well．
Only after a bitter struggle was the aim achieved．
Only the teachers are allowed to use the room．（不倒装）
Only five men were hurt in the accident．（不倒装）
注意,only和所修饰的状语如果不在句首,则不倒装.
如：
The boy was helped out only when his father arrived in a hurry．
Only then did he realize the importance of English
只有在那时候他才意识到英语的重要性.
only then ,是过一小会儿的意思,一般用在句首,引导倒装句.
例句Only then did he realize the importance of English．
解析：在句首的only如果后面跟了副词、介词短语或从句等状语,则主句用倒装结构.如only后跟的是主语,就不用倒装结构了.
再比如
Only when the war was over in 1918 was he able to get back to work．(倒装句）
Only five men were hurt in the accident．（不倒装）

B一般过去时 only then 到那时,后面要用倒装语序.
直到那时她才意识到引起了多大的伤害.（造成损害在她意识到之前,是过去的过去,用过去完成时）

这是倒装句.only位于句首修饰壮语要倒装 只有倒那时我才将会有机会实现我的梦想.will 是谓语的一部分因倒装提前了.再如 only in this way can you learn english well是only引起的倒装句,will 是助动词,如果这个句子...