光学分析法
参考答案：
是基于物质发射的电磁辐射或物质与辐射相互作用后产生的辐射信号或发生的信号变化来测定物质的性质，含量和结构的一类仪器分析方法。
One Sunday morning, Li Ming and his grandpa are 1.
feeding the bird in the cage. The bird was unhappy 2.
because it had enough food and water. Li Ming.did not 3.
know why not. The next morning on his way to school, 4.
Li Ming saw some birds flew in the sky. Then he thought 5.
about the lonely bird in the cage. He decided to persuade his 6.
grandpa to set the bird free. When he got to home, he said 7.
to his Grandpa,“Birds also need friends!” To his delighted , his 8.
grandpa agreed.The bird set free. Grandpa and the children 9.
were very happy to see the bird flying away in the sky. 10.
B/L is the abbreviation for______
A．letter of credit
B．buying contract
C．commercial invoice
D．bill of lading
