phr. Chinese is difficult, but I will try hard (in learning the language).
phr. although... but...
phr. Although he is not smart, he studies really hard.
phr. She was very busy at work, but she still managed to stick to her exercise regime.
phr. Although it rains, it is not cold.
phr. I sent him an email but received no reply.
phr. The house is old, but it is very clean.
phr. I do not know how to solve this exam question, but I made a lucky guess.
phr. This garment is very light, but very warm.