句意：——当我和史密斯先生谈话时，我总是有点紧张。——放松点。他很严格，但他对学生很好。

考查情景交际。It doesn’t matter没关系；What a pity真遗憾；Take is easy放松点；Take your time别急，慢慢来，根据句子I’m always a little nervous when I talk to Mr Smith和He is strict ,but he is kind to his students可知，应该是安慰对方别紧张，放轻松，故选C。