Swallows help keep cattle in barns healthier by ___________. A. eating infected skin B. consuming insects C. singing

Đáp án B

Chịm én giúp giữ cho gia súc trong chuồng khỏe mạnh hơn bằng cách

A. ăn da bị nhiễm bệnh                                            B. ăn côn trùng

C. hót                                                                         D. làm cho những con quạ vui vẻ hơn

Dẫn chứng: As well, swallows feed on insects that can cause infections in cattle. Thus, a farmer who has many swallows in his barn may actually have healthier animals on his farm.