题目

 Cold weather can be hard on pets, just like it can be hard on people. Sometimes owners forget that their cats are just as used to the warm shelter (住所) as they are. Some owners will leave their animals outside for a long period of time, thinking that all animals are used to living outdoors. This can put their pets in danger of serious illness. There are things you can do to keep your animal warm and safe.  Keep your pets inside as much as you can when the weather is bad. If you have to take them out, stay outside with them. When you're cold enough to go inside, they probably are 在DNA分子的一条单链中相邻的碱基A与T的连接是通过（ ）A．肽键 B．—磷酸—脱氧核糖—磷酸—C．氢键 D．—脱氧核糖—磷酸—脱氧核糖—