The correct answer in this case is "we"
Us is also correct but in that case the sentence would not be an elliptical one. If you use "we" then the sentence is both correct and elliptical which fits the description of the question.
An experimental group<span> is the </span>group in an experiment that receives the variable being tested. One variable is tested at a time. <span>The </span>control group<span> is defined as the </span>group<span> in an experiment or study that does not receive treatment by the researchers .</span>
The sentence that has the correct subject-verb agreement is the last one:
Saturn, along with Jupiter and Uranus, has rings that encircle the planet.
In the first sentence, it should be - have several...
In the second sentence, it should be - rotates every...
Signs and symptoms include respiratory symptoms and include fever, cough, and shortness of breath. In more severe cases, an infection can cause pneumonia, severe acute respiratory syndrome, and sometimes... you know.
