Although it was autumn, the snow was already beginning to fall in Tibet. Our legs were so heavy and cold that they felt like blocks of ice. Have you ever seen snowmen ride bicycles? That's what we looked like! Along the way children dressed in long wool coats stopped to look at us. In the late afternoon we found it was so cold that our water bottles froze. However, the lakes shone like glass in the setting sun and looked wonderful. Wang Wei rode in front of me as usual. She is very reliable and I knew I didn't need to encourage her. To climb the mountains was hard work but as we looked around us, we were surprised by the view. We seemed to be able to see for miles. At one point we were so high that we found ourselves cycling through clouds. Then we began going down the hills. It was great fun especially as it gradually became much warmer. In the valleys colorful butterflies flew around us and we saw many yaks and sheep eating green grass. At this point we had to change our caps, coats, gloves and trousers for T-shirts and shorts. From this passage we know it is  _   when they had their bike trip.
summer spring winter fall.