We generally have four people working in the shop, but at ____ periods we employ extra hands.
A、top
B、rush
C、tip
D、peak
Why is compared to a fertilizer in Para. 3?
A、They both absorb light.
B、They both store heat.
C、They both help plants grow.
D、They both cause global warming
1.In each of the following groups of words, there are four underlined letters or letter combinations marked A, B, C and D. Compare the underlined parts and identify the one that is different from the others in pronunciation.