The study shows that karst breccias are the direct sign of paleokarst.

研究表明，岩溶角砾岩是识别古岩溶作用最直接的标志；

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They detected activity of the retroviral enzyme reverse transcriptase, a direct sign of retrovirus replication.

他们发现活性的逆转录酶反转录，直接签署的逆转录病毒复制。

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MRI can show some of the indirect signs of disc disruption and CTD can show the direct sign of disc disruption.

常规MRI仅能显示部分腰椎间盘破裂的间接征象，要明确腰椎间盘破裂需行ctd。

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The Direct Marketing Association keeps a list of those who sign up at its site to opt-out of direct mail.

FORBES: Yellow Pages: No More Waste on the Stoop

But many Iraqis are insisting on direct elections, calling them a sign of control over their own country.

CNN: U.N. help sought on Iraq vote

Instead of asking the public for a one-off donation (as what may have happened previously with door to door charity collectors or events such as telethons) collectors try and get people to sign up to a direct debit scheme where monies are deducted from their bank accounts each month.

CNN: Face to face charity