Problem: Warsaw Pact:

The multi-national Communist armed forces' sole joint action was the Warsaw Pact invasion of Czechoslovakia in August 1968. All member countries, with the exception of the Socialist Republic of Romania and the People's Republic of Albania participated in the invasion.

The Socialist Republic of Romania supported the invasion of what country?
---
A: unanswerable


Problem: 2008 Sichuan earthquake:

On the evening of May 18, CCTV-1 hosted a special four-hour program called The Giving of Love (simplified Chinese: 爱的奉献; traditional Chinese: 愛的奉獻), hosted by regulars from the CCTV New Year's Gala and round-the-clock coverage anchor Bai Yansong. It was attended by a wide range of entertainment, literary, business and political figures from mainland China, Hong Kong, Singapore and Taiwan. Donations of the evening totalled 1.5 billion Chinese Yuan (~US$208 million). Of the donations, CCTV gave the biggest corporate contribution at ¥50 million. Almost at the same time in Taiwan, a similarly themed programme was on air hosted by the sitting president Ma Ying-jeou. In June, Hong Kong actor Jackie Chan, who donated $1.57 million to the victims, made a music video alongside other artists entitled "Promise"; the song was composed by Andy Lau. The Artistes 512 Fund Raising Campaign, an 8-hour fundraising marathon, was held on June 1 in Hong Kong; it was attended by some 200 Sinosphere musicians and celebrities. In Singapore, MediaCorp Channel 8 hosted a 'live' programme 让爱川流不息 to raise funds for the victims.

How much did Jackie Chan donate to support?
---
A: $1.57 million


Problem: Printed circuit board:

Areas that should not be soldered may be covered with solder resist (solder mask). One of the most common solder resists used today is called "LPI" (liquid photoimageable solder mask).  A photo-sensitive coating is applied to the surface of the PWB, then exposed to light through the solder mask image film, and finally developed where the unexposed areas are washed away. Dry film solder mask is similar to the dry film used to image the PWB for plating or etching. After being laminated to the PWB surface it is imaged and develop as LPI. Once common but no longer commonly used because of its low accuracy and resolution is to screen print epoxy ink. Solder resist also provides protection from the environment.

What doesn't provide protection from the environment?
---
A: unanswerable


Problem: Annelid:

Earthworms make a significant contribution to soil fertility. The rear end of the Palolo worm, a marine polychaete that tunnels through coral, detaches in order to spawn at the surface, and the people of Samoa regard these spawning modules as a delicacy. Anglers sometimes find that worms are more effective bait than artificial flies, and worms can be kept for several days in a tin lined with damp moss. Ragworms are commercially important as bait and as food sources for aquaculture, and there have been proposals to farm them in order to reduce over-fishing of their natural populations. Some marine polychaetes' predation on molluscs causes serious losses to fishery and aquaculture operations.

What do some polychaetes eat that has been causing problems?
---
A:
molluscs