题目内容：

    Language learning apps are very popular now and offer opportunities to learn vocabulary and practice grammar. But there has been a discussion about just how effective such apps can be.

Among the most popular apps are Duolingo and Busuu. A previous research found positive results on the use of them. But it mainly concentrates on studies with learners who had signed up for language courses and these apps worked as an after-class support, so the results were not always reliable. A recent study of 4,095 Busuu users has been carried out to find out if users can actually learn a language with an app.

Busuu provides learning materials for 12 different languages. It offers special models where some contents are available for free while some contents are not, We find that its users are an even mix of men and women. More than half consider themselves to be at the beginner level as there is a decrease in users as their language levels go up. Most people use the app because of personal interest, or because they want to study or live abroad. Females tend to use it less often but for longer periods of time than male users.

Getting any feedback on Busuu depends on whether your answer is correct or not. While it is helpful, this is not the sort of feedback language teachers prefer, as it does not explain why the answer is right or wrong. In spite of this, feedback in the app is very highly rated.

More than 92% of the people state that the app has met their expectations and 86% consider the app as very good or good. In fact, more than 80% of the users surveyed strongly agree that using the app has helped them improve their knowledge of the language they are learning.

Besides, language learning apps also create an environment where mistakes are only known to the users, and this can address the performance anxiety that many learners suffer from when asked to speak a foreign language. So language teachers should encourage their students to use them to do the grammar work, leaving precious class time for more language communication.

1.Why weren’t the results of the former research always dependable?

A.Because it used out-of-date methods.

B.Because it just focused on positive results.

C.Because it was only carried out before class.

D.Because it only considered users of a limited type.

2.What can we learn about the app Busuu from the text?

A.All the contents are free to use. B.It’s used by more advanced learners.

C.Most users consider it satisfying. D.It’s more popular with female learners.

3.Which of the following can probably replace the underlined word address?

A.Deal with. B.Write down. C.Turn to. D.Speak of.

4.What is the main idea of the text?

A.Students won’t suffer anxiety in learning languages by using Busuu.

B.Language learning apps are effective and satisfactory to language learners.

C.Language learning apps are very popular with most language teachers.

D.Students should be required to use apps for homework after class.