Which verb form is used to indicate the perfect tense?

a. verb + -ed
b. be + verb + -ing
c. have + been + verb + -ing
d. have + verb + -ed

Which piece of evidence would best support reason #1? othe history of using animals for research extends asfar back as 322 bce, when early greek physician-scientists, such as aristotle and erasistratus,performed various experiments on living animals.animal research played an essential role in thedevelopment of herceptin and tamoxifen, twomedications that have already saved the lives ofthousands of women who have been diagnosed withbreast cancer.even those who believe in testing on animals when it is hnecessary for vital medical research practice what isknown as "the 3 rs-reduction, refinement, andreplacement to reduce the number of animals usedfor testing.biologists believe that chimpanzees share at least 98.4percent of the same dna as humans and gorillas shareat least 97 percent, making primates a popular andlikely choice for the testing of products intended for humans

How does the poem’s mood and tone change in each of these stages? odes and elgies

If the poem is about going mad when love is lost, what would happen if love didn’t die? identify the independent clause. a if the poem is about going mad when love is lost b if love didn't die c what would happen d when love is lost