Allen had to call a taxi because the box was ____________ to carry all the way home.

Now more and more children leave their parents when they grow up. It makes the old feel         .

— Have you ________ watched the dolphin show in the Ocean Park in Hong Kong?—Not _________.

Alice explains things very well, what she says can be understood very ＿＿＿.

—I don’t know much about computer.—I don’t know,      . Let’s go and ask our computer teacher for help.