The lack of the two derived types is an interoperability problem because abstract types cannot appear in an XML instance document.

缺少这两个派生类型是一个互操作性问题，因为抽象类型是不能出现在XML实例文档中的。

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Another problem is the use of implicit types.

另一个问题在于对隐式类型的使用。

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Good threat signature identification will be an ongoing problem as new types of threats emerge.

随着新威胁的不断出现，大量威胁签名认证将一直是个问题。

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Officers have said the main problem on Merseyside is with pit-bull terrier types, but all illegal dogs will be collected.

BBC: NEWS | UK | England | Merseyside | Merseyside's dogs amnesty begins

The problem, by now, is that the GOP has become heavily-infested by two conservative types: the whacko-religionists and the ethno-nationalists.

FORBES: What The Republicans Must Do To Rebuild, And Attract Future Voters

The problem with being too happy about a "good year" (and here the title-or-bust types are on to something) is that next year, the standard for "good" ratchets up, gets a little harder.

WSJ: Five Thoughts on the Knicks