✔ 最佳答案
Generally things expand when heated and contract as they cool.
Sometimes, when things get colder (such as ice at certain temperatures), bonds form that actually push the molecules apart a bit. This causes expansion while cooling (or contraction while heating, as these bonds break), but this is never the case for a very wide range of temperatures. It's also certainly the exception and not the rule. Most bonds actually bring molecules closer together as they form.
This means that if you cool ice which starts at it's melting temperature, it thermally contracts; then starts to expand for a bit, then starts to contract again, and continues to contract until it reaches absolute zero (at which point you of course cannot cool it further.
