'grasp the key' is correct and usable in written English.
You could use this phrase in a sentence to indicate the importance of understanding key concepts or ideas. For example, "In order to succeed in this course, you must grasp the key concepts."
"Governors need focused, easy-to-read briefing which enables them to grasp the key points quickly".
The present semi-analytical study allows us to grasp the key parameters involved in the primary/sub-resonant responses.
When refer to the spirometric criteria for asthma diagnosis, only 34.7% (17/49) in the intervention group and 24.6% (15/61) in the control group could grasp the key points of the guidelines well (P = 0.096).
The majority of complaints I've heard from Priority Inbox users ("It's still showing me junk mail!") are from people who basically don't grasp the key fact that the algorithm needs to be trained to get good, which is hard to do if you're primarily viewing email over the phone or through Mac Mail.
Do not foolishly embrace Options until you grasp the key concepts of buying and selling stocks.
The data are presented in an easy to understand and informative way which a busy reader can easily grasp the key findings.
Until I looked at the details of Kleinbard's paper, I hadn't grasped the key point, which is the nature of Cain's nine-per-cent tax on business profits.
"He's good at quickly grasping the key issues and saying, 'I'd think about this, this and this.' " This is Sam Zell the seer, who believes he can anticipate boom-and-bust cycles.
Our study suggests that grasping the key points of stump revision surgery and an optimized surgical strategy are of paramount importance to the outcomes of stump revision.
Roberto Mancini has come through with his promise to change the club's history and from here they can surely embrace a future in which they seem intent on grasping the keys to the football universe.
The prime minister has yet to grasp the maths key stage 2 concept of averages.
