四、综合填空
Have you ever visited Longmen Grottoes or Yungang Grottoes? Around 1,800 years ago,
Chinese 1.
artists
(art) made sculptures in mountains. Over the years, these sculptures
2.
have gone
(go) through earthquakes, floods and wars. Now 3.
in
the 21st
century, however, they are facing an even 4.
bigger
(big) danger—tourism. Too many
tourists go to visit those grottoes every year and this 5.
certainly
(certain) does harm to
the grotto sculptures. Do you know why?
According to a study, the CO₂ that visitors breathe out has made the air more acidic (酸性的). Also, visitors bring in microorganisms (微生物). Filled with
6.
excitement
(excite)
about seeing the ancient art, some tourists can't help touching the grotto sculptures—this
7.
causes
(cause) their surfaces to change colours.
When we visit the grottoes, we can often see a sign saying, "No Flash (闪光灯)!" or "No
Photos!" This is 8.
because
the strong light can be bad for the sculptures, especially
those with colours. The light can easily make them lose colours.
To protect those ancient cultural treasures, recently the workers have controlled (控制)
9.
the
number of the visitors. They have also offered digital tour shows instead of
10.
letting
(let) too many people visit the caves at a time.