These plastic flowers look so ________that many people think they are real.[ ]

uncertain ________ side effect the medicine will bring about, although about two thousand patients have taken it.

We must ________ our task, however hard it is.

There is clear evidence_____the most difficult feeling of all to interpret is bodily pain.[ ]

here anything wrong, Bob You look sad.—Oh, nothing much. In fact, I __________ of my friends back home.