多长时间

nǐ děi děng duō cháng shí jiān

你得等多长时间？

How long you have to wait?

nǐ dǎ suàn qù duō cháng shí jiān

你打算去多长时间？

How long are you going to go?

yī chǎng kǎo shì shì duō cháng shí jiān

一场考试是多长时间？

How long is an exam?