单项选择题
A．About half of Panama lies east of Miami. B．Panama is squeezed into the narrowest portion of Central America. C．Panama offers the lowest point in the North American continental divide. D．All of the above are tru
A．spelling B．ideas C．whole words D．expressions
A．to make some sound experiments in the oceans B．to collect samples of sea plants animals C．to estimate the length of cable that was to be made D．to measure the depths of two oceans