Answer
Correct Answer is a.(spikes)
Explanation:
option a is correct because here serves, rotation and spikes all the three words are using as object.
The volleyball team practiced their serves, rotations, and spikes.
option b cannot be correct because here spiking is used as a verb and sentence(The volleyball team practiced their serves, ) is in past indefinite form and we cant use word spiking here because this form of verb is used in continues form of sentences only.
Option c cannot be correct as because in this option ""spikes the ball" spikes is used as a verb which can be used in present indefinite form of sentence only but here sentence is in past indefinite form.
Again option d cannot be correct because in this option ""spikes over the net" spikes is used as a verb which can be used in present indefinite form of sentence only but here sentence is in past indefinite form.
Answer:
As beams of particles and their associated energy are given off, the pulsar will lose energy slowly, which will decrease the rate of its rotation. The frequency of pulses would therefore decrease, so that fewer pulses are observed in a given time span. The strength of the pulse signal will also decrease so the pulses will become fainter. Eventually, the pulsar should rotate so slowly and have such a low emission of radiation that it would no longer be observable.
Answer:
The alternative energy sources are defined as those resources that are used in place of the natural and non-renewable resources. This resources plays an important role in the conservation of natural resources.
The fossil fuels are the resources on which the people are directly dependent. Burning up of these fossils leads to the emission of carbon, which has a direct impact on earth. A small increase in the amount of carbon dioxide can lead to the increase in the surface temperature of earth.
In addition to this, these fossil fuels such as coal, petroleum, oil and natural gases are found to be present in a limited proportion, and it is a very expensive process to obtain these resources, so sustainable development method must be adopted in order to save this natural resources for the future generation.
Some of the examples of alternative resources that are widely used in place of fossil fuels are wind energy, solar energy, tidal energy, biomass energy and bio-fuels.
Thus, it is very important to develop and use alternative resources.
