Space travel is definitely bad for astronauts’ bones, reducing their bone density(密度) afte

Space travel is definitely bad for astronauts’ bones, reducing their bone density(密度) after only a month of weightlessness, according to French research published on Friday.
Laurence Vico and his fellow workers at St Etienne University called for more research into the effects of microgravity, after their study of 15 astronauts from the Russian MIR station showed bone loss continued throughout space flights.
“Bone loss was especially striking in four astronauts, ” the scientists reported in the Lancet Medical Journal.
They measured the bone mineral density (BMD) of bones in the forearm(前臂) and lower leg of the astronauts who had spent one to six months in space.
The BMD loss was significant in the tibia(胫骨) of the lower leg, a weight-bearing bone, but barely changed in the radius(桡骨) of the forearm. “Our results indicate the need to investigate not only different bones, but also different areas of the same bone since not all sites of the skeleton (骨架) are similarly affected by space conditions, ” they added.
Without gravity the body isn’t bearing any weight so there is no need for calcium (钙) which makes bones strong, and it bees empty into the bloodstream.
The research team suggested in future scientists should try to determine if the loss of bone density was only on weight-bearing bones on longer flights, also the possible recovery after returning to Earth.
【小题1】French scientists did their research on Russian astronauts, because     .A．they only cared for the Russian astronautsB．they were not interested in their own astronautsC．the Russian government invited them to do their researchD．the Russian astronauts worked in space for a long time【小题2】 Scientists have found that     .A．the BMD loss may cause serious illness to astronautsB．the BMD loss may cause some change in astronauts’ bodiesC．astronauts shouldn’t care about the BMD lossD．astronauts should take some calcium before space travel【小题3】 What cause the BMD loss to astronauts, according to this passage?A．The food they eat in space.B．The drinks they take in space.C．The temperature in space.D．The gravity in space.【小题4】In the third paragraph, the word “striking” means     .A．unusualB．simpleC．weakD．slowD