If I — a camera with me, I would have taken some photographs. / We would have bought a new stero system if we — enough money.

ব্যাখ্যা: Main clause---এ 'would have taken' / 'would have bought' থাকায় Third Conditional অনুযায়ী If clause---এ Past Perfect tense হতে হবে। Past Perfect---এর auxiliary verb 'had' এবং মূল verb 'have'---এর V3 'had' একসাথে বসে 'had had' হবে।