A Korean survey shows that shopping cart handles are the most bacteria-carrying items among some ________used objects.

Polar bears live      on sea ice，which they use as a platform for hunting seals

________，the search engine just gave me some brief introductions rather than the whole content of the book to read.

7. The questionnaire takes       ten to fifteen minutes to complete and can be used along with the assessment interview.

Although I majored in English, language _______ became a challenge when I set foot in the USA for the first time.