Why does "look" use past tense? The lessons from Canada’s attempts to curb its house-price boomIN MATTERS of finance, if not climate, Canada is usually temperate. It was barely moved by the economic storms that blew the roof off America and Europe in 2008-09. Its banks were steady, it was argued, in part because they were shielded from the ferocious competition for market share that pushed banks elsewhere into hazardous loans. For all that, in its housing market Canada has lately become a place of extremes. Household debt has climbed to almost 170% of post-tax income. House prices rose by 20% in the year to April. 【Looked at】 relative to rents, they have deviated from their long-run average by more than any other big country. The Economist covers in its global house-price index. In Toronto, one of two cities, along with Vancouver, where the boom has been concentrated, rental yields are barely above the cost of borrowing, even though interest rates are at record lows. In its twice-yearly health-check on the