No doubt means 'probably' or 'I suppose' , not 'certainly' .

No doubt it'll rain soon. / You are tired, no doubt. I'll make you a cup of tea./

To say that something is certain, we can use there is no doubt that (formal) ,without any doubt(formal), certainly , definitely.

There is no doubt that world is getting warmer.(NOT No doubt the world is getting warmer.)

Note: Doubtless is similar to no doubt (but more formal); Undoubtedly is similar to there is no doubt that.

Hello Guys ! How's everything ? This post is dedicated for some common mistakes in English. You should be careful when you you are speaking English and try out to speak correctly. Now , take a glimpse on common mistakes here beneath:

Which :                                                                                

                    Don't say:                                          Say:

Pizza , which it was invented in Italy,     Pizza , which was invented in Italy,  

• When Which is a relative pronoun, don't use another pronoun after it.

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   Do/Play/Go

  Do not say:                                              Say:

He makes several sports.                  He does several sports.

You should make more exercise.        You should do/take more exercise.

I play a lot of sports.                         I do a lot of sports.

we often do swimming.                     We often go swimming.

•  Use the verb do with the general word sport.
• Play van be used when the actual sport is named, e.g. I play a lot of tennis.
• Use the verb go before sports enfing in -ing.
• Use the verb do or take with exercise.

Well guys !That's all about common mistakes . However, they are unlimited I am going to tell something more about it next times.Later, comrades...!!!9