it's too hot today.but we could go swimming 里面的COULD为什么是过去式啊

it's too hot today.but we could go swimming 里面的COULD为什么是过去式啊 It is _____ hot today.Let's go swimming. it's a fine day today shall we go swimming?____ but we need 英语翻译It was too hot to go further and they wished they could 填空题：It's very hot today,Ann.() you like to go swimming with today is hot but it's cold it\'s hot summer.we go swimming and eat ice cream. this piece of paper is beautiful.But it's too small,Could yo This piece of paper is beautiful .But it's too small .Could This piece of paper is beautiful.But it's too small.Could yo could的过去式是么 We-----but could------nothing.