they are swimming ____(happy) in the river为什么填happily?有句式的话更好!

are they swimming or running 回答 They (swim;are swimming)in the river They are swimming.(改为一般疑问句) They are swimming.改为否定句 THEY ARE THE SYMBOL__ __? Look!He __ in a swimming pool.A.swimming B.are swimming C.swims D.is swimming They are swimming in the river 还是（they are go swimming in the river) They and I are swimming还是is swimming或am swimming Are they swimming?(做否定回答）_____,they ______. They are more-------【act】,So they prefer swimming and climbing They are visiting the Great Wall.=They are __ __ __ __ the Great Wall. some of __(me) are good at swimming They are small houses变成感叹句__ __ __ they are! There ( )some fish in the riverand they are swimming happily They are going swimming tomorrow?用camp改为选择疑问句 They are (swimming in the river).对画线部分提问 They are swimming in the river是什么句型?如题 They are going to__ A.swim B.swiming C.swimming