Mark the letter (A, B, C or D) on your answer sheet to indicate the word or phrase that is CLOSEST in meaning to the underlined part in each of the sentences from 34 to 35.

Billy, come and give me a hand with cooking.

A. help

B. prepared

C. attempt

D. be busy

Khi đun nóng axit photphoric đến khoảng 400   - 450 0 C , thu được:

A. axit metaphotphoric (HPO₃)

B. axit điphotphoric (H₄P₂O₇)

C. axit photphorơ (H₃PO₃)

D. anhiđrit photphoric (P₂O₅)