When I speak English, I always speak off and on. Could you please tell me how to develop oral skills of making connected speech?
I assume you mean you speak in bursts, when you say you‘speak off and on’. The first thing to be aware of is that most speaking is the product of interaction with another person, or with other people. We rarely give speeches. This means we have to train ourselves to understand what others are saying and then to reply to what we have heard. There are different kinds of conversation, which require different skills. For example:
Exchange of information. This is one of the most common kinds of everyday interaction. Your friend tells you about things he/she enjoys doing in his/her spare time. You listen carefully, then you tell him/her what you enjoy doing in your spare time. You answer like with like. The chances are that you will use the simple present tense a great deal in this kind of exchange.
Narration. Your friend tells you about an experience in the past tense (how he/she missed the bus, was late for work, what the boss said, etc.). You listen carefully, then tell a story of your own. The chances are you will use the simple past and past progressive tenses a great deal in this kind of exchange. It’s always easier to tell a story in chronological order: begin at the beginning, go on to the main event, then conclude the story.
Exchanging views and opinions. Your friend tells you what he/she thinks about something, first by describing a situation, then saying what his/her opinion of it is and giving reasons. You listen carefully, then reply in the same way. You are likely to state facts (something you read in the paper), give an example or examples, and then say what you think of it. You are likely to use phrases like‘In my opinion...’, ‘I think ...’, ‘I agree with what you say, but ...’, ‘I’m afraid I disagree. I think ...’and so on.
交流看法和观点。你的朋友告诉你他/她对某事的看法，他/她先描述一段场景，然后发表他/她的意见，并给出理由。你仔细听，然后以同样的方式作出回答。你有可能陈述事实(你从报纸上读到的东西)，给出一个或几个例子，然后说明你的看法。你很可能用些诸如In my opinion...，I think...，I agree with what you say, but...和I’m afraid I disagree. I think... 等短语。