46. Bell experimented with ways of transmitting..................over a long distance. SPEAK
=> Bell experimented with ways of transmiting speech over a long distance. (SPEAK)
Sau of+N => speak-> speech
47. It is .........healthy.................. to eat too much sugar and fat. HEALTH
It is +adj+to...: nó như thế nào để
=> health-> healthy
48. After having taken an aspirin, her headache........................ APPEAR
Sau khi uống thuốc giảm đau, cơn đau đầu của anh ấy biến mất
=> appear-> disappear
49. Our main............................... to export are rice, coffee and rubber. PRODUCE
sản phẩm chính để xuất khẩu=> product
Căn cứ vào từ "are" => products
50. This form must have the............................. of the writer. SIGN
the+N => signature(chữ ký)