单项选择题
[听力原文] M: The pen costs $13, but I only have $7. W: I have $6. Would you like to borrow it
A.$4. B.$6. C.$7. D.$11.
A.金属在诸多特性中以强度最为重要。 B.具有强度的金属有多种用途。 C.金属有许多有用性能,其中强度最为重要。 D.金属坚硬耐磨才是其最重要的性能。
A. didn't know B. don't know C. hadn't know D. haven't known