they couldn't have done better是什么意思

My parents___here last night,but they couldn't. ______,they couldn't solve the mystery they were surprised that a child should work out the problem____they themselves couldn't. couldn't翻译 couldn't是什么意思 翻译:they looked for the treasure for many days,but they still couldn't find any Couldn't find NTLDR couldn't 和 shouldn't If it should snow tomorrow, they couldn’t go out.这是虚拟语气吗？为什么？ Error:loader couldn't initialize service!