Doyle learned that only one side of the moon is ever visible from earth. he wants to investigate how the moon moves around the earth and to understand how this motion causes the phases of the moon. which kind of scientific investigation should he use? development of a model a review of existing work a field study

 Create a model.

Explanation: He should develop a model of the Earth-Moon-Sun system. This will let him clearly see how the Moon must move in order for one of its sides to always face away from the Earth. If he uses a light source for the Sun in his model, it will also show how the phases of the Moon happen. The real Earth-Moon-Sun system is too large for him to observe it in the same way.

she was killed in her home during hurricane katrina. b.she was relocated to another town after hurricane katrina. c.she died trying to get victims of the hurricane to safety. d.she is still missing — police do not know where she is.

the pronoun reference replaces a noun, but you have to make sure there's no room for confusion.

in the first sentence "her" could be referring to shely or to the sister. the answer there is "shelly called her sister and told her about the new baby."

in the second sentence "it" could be referring to the roof or the floor. the answer there is "since the roof leaks on the family room floor, we need to repair the roof."