简述果蔬采收成熟度的确定因素有哪些?
参考答案:
①果蔬表面色泽②硬度和饱满程度③果蔬生长状态④生长期⑤果梗脱落的难易程度⑥主要化学物质的含量与变化。
— I called you at six yesterday, but there was ______ answer.
— Did you? I ______ dinner at my friend's home.[ ]
A: not an; had
B: no; was having
C: not; was having
D: no; had
传导是指()的物体各部分间的能量交换现象。
A.直接接触
B.间接接触
C.不接触
D.绝缘