Investment in environment __ present-day economic development.

She will stop showing off ______ (如果没有人把注意力放到她身上).

Our company __ (不能和解) on such terms.

These pills should (keep) __ out of the reach of children.

Why has academic work become more specialised？

Books have always been the main tools for teaching.

But a vast number of new tools have come to use in this 【S1】__

century. Take audiovisual aids for an example. "Audiovisual" 【S2】__

means "hearing-and-seeing". These aids to learn include 【S3】__

films, television, audiotapes, videotapes, slides, recordings,

charts, or graphs. In many schools there are language 【S4】__

laboratories where students studying foreign languages can

listen to recordings of natural speakers. The students can 【S5】__

record their speech and play back tape to hear their 【S6】__

own pronunciation. Tremendous strides have been made

in television instruction. Thousands of schools are now

using television as part of the irregular teaching program. 【S7】__

Hundreds of closed-circuit television systems have been

set in schools and colleges. There are more than 200 【S8】__

educational television stations in the United States

majoring in programs of many types. For such large 【S9】__

audiences, television stations can spend more money

to preparing programs than any one school could spend. 【S10】__

In television classrooms, students may see expensive

scientific equipment in use. They may see close-ups of

historical documents. Or they may hear talks by famous

scientists or writers.

【S1】