Asbestos..........................
The answer is tighten and contract.
In order for the students to pull the rope their muscles will need to tighten and contract so they are able to continuously pull with all their strength and power. Relaxed or twitched muscles will result in release of the rope.
1 - sentence
2 - copy and paste
3 - make spelling error
Explanation : In order to write a research paper, the objectives of writing it should be very clear. We should not write irrelevant sentences that don not relate with the aim of the paper. While writing the paper in our own words, we should ensure not to copy and paste from other journals and keep the grammar right. The sentences should be well phrased and we should get our paper checked by someone for the purpose of proofreading.