1.raise vs rise
When used as a verb they both have the same general meaning of "to move upwards", the main difference is that rise is an intransitive verb (it does not take an object), while raise is a transitive verb (it requires an object):
rise (v) Something rises by itself
Example 1: The sun rises in the east.
Example 2: Luther rose slowly from the chair.
Example 3: I will rise tomorrow morning at 6 a.m. to walk the dog.
Rise is an irregular verb: rise / rose / risen
raise (v) Something else is needed to raise something.
Example 1: Linda raised her hand.
Example 2: The government is going to raise taxes.
Example 3: He raised himself into a sitting position.
Raise is a regular verb: raise / raised / raised
2.Assume vs know vs think
To assume is a regular verb that means to suppose something to be the true, but without proof.
Example: I assume you're here to learn English.
To know is an irregular verb that means to be absolutely certain or sure about something, usually through observation, inquiry, or information.
Example: I know I should practise English every day, but I never seem to have the time.
To think is an irregular verb that means to have a particular opinion, belief, or idea about someone or something.
Example: I think English is a global language.
Note - If you need to remember which one to use, memorise this sentence: Why do some people assume they know what other people think about something?
3.overtake vs takeover (take over)
Overtake is a verb. It can mean to go beyond something by being better, or if you're driving to come from behind another vehicle or a person and move in front of it.
Example: You should always check your rear view mirror before you overtake another car.
Takeover as a noun is used when one organisation gains control of a company by buying most of its shares.
Example: In September 2006 Merck announced their takeover of Serono SA.
Take over as a phrasal verb means to get control of a company by buying most of its shares.
Example: Merck finally took Serono over in 2007.