Thisstrangerisfamiliar___this area.[ ]

Black holes can not be seen directly, so determining the number of them is a___________ task. [ ]

Tom likes playing ________ football, but his sister likes playing ________ piano.

oft, in a _______ from tradition, has already released similar touch-friendly Office apps for Apple Inc’s iPad and iPhone.

John, you look worriedAnything wrong?—- Well, I _______ a test and I’m waiting for the result