It's easy to go up to a third scale, but difficult to a seventh.

音阶上升三度容易，上升七度就难了。

youdao

Curiosity, he argues, is the third key factor—and a difficult one to preserve.

他认为，好奇心是第三个关键因素，也是一个很难保持的因素。

youdao

Next the researcher introduced a third option, a third paddle that would initiate a new trial, giving the dolphin the choice of passing on difficult trials.

接下来，研究人员引入了第三种选择，用第三只桨启动一个新的试验，让海豚选择跳过困难的试验。

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America's third party at that time -- The People's Party -- had a difficult decision to make.

VOA: special.2010.07.01

This led to a third and more difficult problem, the question of who should pay for the health care program.

CNN: Commentary: Grateful Dead on health care

Andrews, the home of golf, by picking up his ball in disgust during a difficult third round and effectively disqualifying himself.

CNN: Bobby Jones: The gentleman who shaped modern golf

London - Billionaire Lakshmi Mittal must have needed nerves of steel as he steered his industry behemoth, Mittal Steel through a difficult third quarter.

FORBES: Mittal's Steel Empire Sees Profit Plummet 64%