Question

Perfect tenses For this section of the test, read each sentence carefully, then fill in the blank spaces with the correct form of the verb given in the parentheses (...). Since the middle of the 20th century, scientists (find) have found ______ cures for many diseases. However, so far no one (discover)______

Answer 1

Since the middle of the 20th century, scientists (find) have found ____found__ cures for many diseases. However, so far no one (discover)__ discovered

Answer 2

Since the middle of the 20th century, scientists have found cures for many diseases. However, so far no one has discovered

Step-by-step explanation:

those are the perfect tenses for (find) and (discover)