制造板牙常选用（）钢。 A.5 CrNiMo B.Cr12MoV C.W18 Cr4
题型：单项选择题
问题：
制造板牙常选用（）钢。
A.5 CrNiMo
B.Cr12MoV
C.W18 Cr4V
D.9SiCr
题型：单项选择题
Farming in the USA today is very different from that 100 years ago. In those days, farmers did not have many machines（机器） to help them. They had animals. 小题1: __ This meant that farms were smaller than they are now. Farmers also worked in a different way in the past. In those clays, farmers grew fruits and vegetables and kept cows, pigs and chickens to feed their families. 小题2: __
Farmers have a very special life in many ways. First of all, they can't leave the job at the end of the day. They live on the farm and there is always work to do. Second, a lot of farm work is outdoors, so the weather is very important for farmers. 小题3: __ A lot of bad weather means farmers will lose money. Finally, farmers work with plants and animals. They understand nature better than other people do .
小题4: __ Spring is a time for planting. Farmers are busy getting the fields ready and then: Planting the seeds(种子). In summer, farmers must take good care of the plants. Some may need water. Other plants may have problems with insects or diseases（疾病）. Then in fall, the fruits or plants are ready for picking. 小题5: __ Winter is a time for rest or for work on the farm machines.
把A---E五个选项填入文中空缺处，使短文完整正确。