That,they calculate,would add 5.7 metres to the braking dist

題目：

That,they calculate,would add 5.7 metres to the braking distance of a car travelling at 100kph.
這裡的 calculate是及物還是不及物?和前面的that

解答：

不及物,與That無關.
That是主語,「they calculate.」是個完整的句子,用來修飾和解釋說明主語「That」..calculate後無動詞,故它在這個句子裡是不及物動詞.