"a few trial" is not correct and usable in written English.
Instead, you could say "a few trials" to refer to multiple attempts or experiments. Example: "The scientist conducted a few trials before reaching a conclusive result."
The early phase of the cash dance has yielded a few trial balloons.
Direct students to work together to review their segments, do a few trial runs and record their final productions.
The secretary opened the box and was unable to resist giving the thing a few trial cranks.
As the argument intensifies, Mark tries to lighten the moment by picking up a nearby golf club and giving it a few trial swings.
A few trial runs, some careful proofing and numerous small adjustments later (a tiny piece of newsprint stuck onto the packing can make all the difference), the finished job emerges: crisp, tangibly different, immensely satisfying.
"They think they want to look like that," said Mr. Adar, who like Mr. Kim, is a disciple of Mr. Geller's, "but once it's in the mouth, it looks horrible, and they say, 'Oh my God.' " To avoid such mishaps, he and others create a few trial veneers — some translucent, some opaque — so the patient can decide.
After a few trials, the warning signal alone caused Kina to decrease the sensitivity of her hearing.
A register of official interests would be laudable, and a few trials of people from Mr Xi's own camp would send a message.
The food itself elicited copious salivation, but, after a few trials, the ticking of the metronome, which regularly preceded the delivery of food, also elicited salivation.
At first, a feasible hole profile, which will be deformed to be a nearby square hole in the bore-expanding process, is obtained by using a few trial-and-errors.
After a few trials, most of the animals started carrying the right tool with them.
