As Microsoft's Grammar Check knows (see second link below), English is a hard language learn.
Here's the brain pattern for sentence comprehension:
Can you see the different brain areas and the different arrows? Sentence comprehension is a complicated task that affected by word choice, word order, word grouping, and conventions. Sample sentences from the paper:
The writer attacked the king and admitted the mistake at the meeting.
The writer that the king attacked admitted the mistake at the meeting.
The pundit that the regent attacked admitted the gaffe at the conclave.
These sentences vary in complexity, and speed of processing. Sentence comprehension is a hidden cause of underachievment in some middle and high school students. They may get along all right with reading and listening to information told 'in context' (in a lesson plan, lecture, or story), but then make huge blunders on brief non-contextual sentences that are presented in the form of questions on tests.
Targeting the source of comprehension problems is often the first order of business. One strange quirk of the brain is that different parts of speech are stored in different areas. Some students have particular problems remembering the meaning of connector words like 'although' or 'until' because they are a bit abstract and they are understood only in relationship to other parts of the sentence. The second step may be troubleshooting specific memory problems (for instance auditory word memory) and devising strategies to overcome them (e.g. imagery).
The Neural Bases of Sentence Comprehension
Microsoft's Terrible Grammar Checker
Owl Purdue English and Grammar Resource