Correct usage of their#!#there#!#they are

Write the usage of electromagnets.

Choose the appropriate usage to fill the sentence : We tried …..hard to get the problem solved without any help.

Assertion: In unicellular organisms, we are not very clear abou usage of these two terms-growth and reproduction. Reason: In unicellular organisms, reproduction is synonymous with growth.

Choose the appropriate usage to fill in the blank : The essence of the talk was …..misunderstood.

Choose the appropriate usage to fill in the blank: In spite of the heat, they marched ......