The phrase "a main form of" is correct and usable in written English.
It can be used when discussing a primary or significant type or category of something.
Example: "In our research, we identified a main form of renewable energy that could significantly reduce carbon emissions."
Alternatives: "a primary type of" or "a key category of".
Players also get to grow vegetables and cultivate food stocks (cows being a main form of sustenance it appears).
One survivor said that the explosion completely destroyed the bus, a main form of intercity transportation for Afghans.
Fatigue crack is a main form of structural damage in flexible pavements.
It must hammer technology companies for loose accounting standards, which include concealing the true cost of stock options, a main form of compensation for executives and staff.
Domestic solar hot water system, as a main form of solar thermal applications in the building sector, is widely used by city residents.
Molecular diffusion is a mass transport mechanism in cell biology, and diffusion is a main form of transport for necessary materials such as amino acids within cells.
The nonprofit group Utility Consumers Action Networkk, suggests on its Web site UCAN.org, that if a cellphone is your main form of communication, you consider investing in a backup battery pack.
Though I am a generally happy person who finds humor in even the most mundane occurrences, as a creative personality whose main form of expression and contribution is through my writing, my emotions lie close to the surface.
I helped put in the docks this year and once cleared rocks on common land with an association member whose main form of recreation seems to be working tirelessly on behalf of the rest of us, but I'm usually a little too busy working on my table-tennis forehand to become too involved.
Instead of a hard-drive, a slot for an SD card acts as the main form of storage.
Only when they went to talk to a health worker at the centre did she discover that, although it is effective against some severe forms of paediatric TB, BCG is unreliable against pulmonary TB – the main form of a disease that recently overtook HIV as the leading infectious killer in the world.
