Q: Some tests are so hard that no one does well on them other tests are too easy and don't really test comprehension.
A: Some tests are are so hard that no one does well on them, other test are too easy and don't really test comprehension.
Is this correct?
There is a grammar error. It is not without punctuation as in the first one, nor is it a com ma as in the second one. It is either a period and two separate sentences (what you have is a run-on sentence OR a semicolon.
Some tests are so hard that no one does well on them; other tests are too easy and don't really test comprehension.
Sra
Some test are so hard that no one does well on them. Other test are too easy and don't really test comprehension.
Is this right?
As far as English goes, except for "Other tests...."
However, the statements omit the majority of tests that do very well in testing comprehension.