SOLAR FLARES

CAE Use of English Part1: Multiple Choice Exercise

For questions 1-12, read the text below and decide which answer (A, B, C or D) best fits each gap.
There is an example at the beginning: (0) A break , B interfere, C disrupt, D disorder.

What are solar flares?

Scientists are warning that an explosion of solar flares could (0)....C disrupt.... communications on Eafth at any time. But what are these sudden bursts of light and what (1).............. them?

A solar flare is a large explosion of magnetic (2)............. in the sun's atmosphere which causes an intense burst of increased brightness. They cannot be detected by the (3)................eye from the surface of the Earth but can be observed through telescopes, space x-rays and thermal imaging (4)................ .

The (5).................... of energy released by a flare can be (6) .................. to millions of 100-megaton hydrogen bombs (7) ...................... at the same time - ten million times greater than that released by a volcanic (8) ....................... . Often lasting just a few minutes, solar flares (9)....................... material to many millions of degrees and produce a burst of radiation across the electromagnetic spectrum, including from radio waves to X-rays and gamma rays.

A flare occurs when energy that has built up in the solar atmosphere is suddenly (10).................. - mostly in the active regions around sunspots. Their frequency varies from several a day, when the sun is particularly active, to less than one a week during quiet periods.

Large flares are less (11) ................... than smaller ones. Solar activity varies within an 11-year cycle at the (12)............................. of which there are typically more sunspots and therefore more solar flares.