When you are cross-examining a witness, you should be careful not to give the witness an opportunity to explain. This is exactly what you'll do, however, if you use adjectives needlessly--
Q. "You couldn't see the collision clearly, Mr. Witness, could you?"
A. "Yes, I could. I had a very clear view of the collision. I was standing right there when it happened--there no way I could have had a better view."
The witness might also reply, "It depends on what you mean by 'clearly.'" In either case, the witness is no longer under your control, and the jury is watching him, not you.
Rather than using adjectives, think about the facts that together can stand in place of the adjective, then turn each of these facts into a separate question. It will make your point as clear as possible, will give the jury a visual image, and will keep the witness under your control--
Q. You saw the collision?
Q. You were standing across the street?
Q. About ten feet from the curb?
Q. The accident happened on the other side of the street?
Q. The street was five lanes total--four lanes plus a turn lane?
Q. And there was also a shoulder on both sides?
Q. It was raining at the time of the collision?
Q. The rain had just started?
Q. And you were headed towards the Denny's to get out of the rain?
Q. Traffic was passing in front of you when the collision occurred?
In this way, you can paint a visual image of a witness who was hurrying through the rain and observed the accident from far away while traffic was passing in front of him. The jury will get the idea that the witness did not have a clear view of the collision without the use of the word "clearly," and the witness will remain under your control.
Source Note: "Controlling the Witness on Cross-Examination," by Michael J. Walter, reprinted in The Litigation Manual: Trial.