首先,要说明的是,并不是每个句子都适合于变成各种时态.
一般现在时态：
Jack is from America.【最好不变化】
He works hard at his lessons.
He like playing football.
He can speak both English and Chinese.
He enjoys singing beautiful songs.
对应现在进行时态：
He is working hard at his lessons.
He is playing football now.
He is speaking to others around him with English and Chinese.
He is enjoying singing the beautiful songs.
过去进行时态：
He was working hard at his lessons.
He was playing football at six last afternoon .
He was speaking to others around him with English and Chinese at ten yesterday morning
He was enjoying singing the beautiful songs at eleven last night .
一般过去时态：
He worked hard at his lessons.
He liked playing football.
He could speak both English and Chinese.
He enjoyed singing beautiful songs.
一般将来时：
He will work hard at his lessons this term.
He shall play football tomorrow morning.
He will learn to speak both English and Chinese.
He will sing beautiful songs at the party this evening.
现在完成时：
He has worked hard at his lessons since the start of this term.
He has been interested in playing football .
He has learned to speak both English and Chinese.
He has been fond of singing beautiful songs.
过去完成时：
He had decided to work hard at his lessons since that exam..
He had been interested in playing football before he was fifty .
He had learned to speak both English and Chinese before he came to China.
He had enjoyed singing beautiful songs before he attended the party.